Liquid crystal display and method of manufacturing the same

ABSTRACT

The invention has an object to provide a liquid crystal display in which a wide angle of view is obtained and a response time at a halftone can be shortened by regulating an alignment orientation of a liquid crystal by the use of a polymer fixation system in which a liquid crystal layer containing a polymerizable component is sealed between substrates, and the polymerizable component is polymerized while a voltage is applied to the liquid crystal layer to fix a liquid crystal alignment. A liquid crystal layer containing a polymer for regulating a pretilt angle of a liquid crystal molecule and a tilt direction at a time of driving is sealed between two substrates arranged opposite to each other. A plurality of stripe-like electrode patterns in which a pattern width is formed to be wider than a width of a space, are arranged so that the liquid crystal molecule is aligned in a longitudinal direction of the pattern when the polymer is formed by solidifying a polymerizable component mixed in the liquid crystal layer while a voltage is applied to the liquid crystal layer.

This is a Continuation of application Ser. No. 11/471,831, filed Jun.21, 2006, which is a Divisional of application Ser. No. 10/109,020,filed Mar. 28, 2002, which is now U.S. Pat. No. 7,113,241.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display in which aliquid crystal layer containing a polymerizable component (monomer oroligomer), which is polymerized by light or heat, is sealed betweensubstrates, and the polymerizable component is polymerized while avoltage is applied to the liquid crystal layer to fix a tiltingdirection of a liquid crystal molecules, and a method of manufacturingthe same.

Besides, the present invention relates to a liquid crystal display of aVA (Vertically Aligned) mode in which a liquid crystal having a negativedielectric anisotropy is vertically aligned, and a method ofmanufacturing the same.

2. Description of the Related Art

A multi-domain vertical alignment mode liquid crystal display(hereinafter abbreviated to an MVA-LCD) is known in which a liquidcrystal having a negative dielectric anisotropy is vertically alignedand a bank (linear protrusion) or a cut portion (slit) of an electrodeis provided on the substrate as an alignment regulating structuralmember. Since the alignment regulating structural member is provided,even if a rubbing processing is not performed to an alignment film,liquid crystal alignment orientations at the time of voltage applicationcan be controlled to be plural orientations. This MVA-LCD is superior toa conventional TN (Twisted Nematic) LCD in a visual angle property.

However, the conventional MVA-LCD has a defect that white luminance islow and a display is dark. The main cause of this is that since an upperportion of a protrusion or an upper portion of a slit becomes a boundaryof alignment division to generate a dark line, the transmissivity at thetime of a white display becomes low and the display becomes dark. Inorder to improve this defect, it is sufficient if an arrangementinterval of the protrusions or slits is made sufficiently wide. However,since the number of the protrusions or slits as the alignment regulatingstructural members becomes small, there arises a problem that it takes atime to fix the alignment of LC molecule even if a predetermined voltageis applied to the liquid crystal, and a response speed becomes low.

In order to solve this problem and to obtain an MVA-LCD which has highluminance and enables a high speed response, a polymer fixation(macromolecule fixation) system is effective. In the polymer fixationsystem, a liquid crystal composite in which a polymerizable component ofa monomer, an oligomer, or the like (hereinafter abbreviated to amonomer) is mixed in a liquid crystal, is sealed between substrates. Inthe state where liquid crystal molecules are tilted by applying avoltage between the substrates, monomers are polymerized into polymers.By this, a liquid crystal layer in which the molecules are tilted(inclined) at a predetermined tilt direction by voltage application isobtained, and tilting direction of the liquid crystal molecule can befixed. A material which is polymerized by heat or light (ultravioletray) is selected as the monomer.

However, the polymer fixation system has some problems relating tounevenness of display when an image is displayed on a completed LCD.First, there is a problem that unevenness of display occurs on an imagedisplay of the completed LCD due to the alignment abnormality of liquidcrystal locally generated in driving the liquid crystal at the time ofmonomer polymerization. Besides, there is also a problem that thereoccurs unevenness of display due to the abnormality of characteristicsof thin film transistors (TFTs) caused by driving of liquid crystal andpolymerization processing at the time of monomer polymerization.

FIG. 21A shows a liquid crystal driving method at the time of forming apolymer (polymerization) in a conventional MVA-LCD to which an alignmentfixation processing by the polymer fixation system is performed. FIG.21B shows the cause of the unevenness of display of the MVA-LCD in whichthe polymer formed by the liquid crystal driving method shown in FIG.21A exists in a liquid crystal layer. Then channel type TFTs are used inthis MVA-LCD.

In general, in order to prevent a ghosting phenomenon, an alternatingvoltage is applied to a liquid crystal layer of an LCD. Then, also in apolymerization step at a stage of LCD manufacture, an alternatingvoltage is applied to the liquid crystal layer to tilt the liquidcrystal molecules, and monomers are polymerized. For example, as shownin a graph of FIG. 21A, a gate voltage Vg=33 V is kept applied to allgate bus lines of a panel display region, and a TFT, which is providedin each pixel, is kept in an on state, and then, a drain voltage inwhich an alternating data voltage Vd (ac)=±7 V is superimposed on adirect-current data voltage Vd (dc)=13 V is applied to all drain (data)bus lines. By this, Vd (dc)+Vd (ac) is written to a pixel electrodeformed in each pixel region. On the other hand, a common electrodearranged opposite to the pixel electrode across the liquid crystal layeris kept at a common voltage Vc=13 V. By this, the alternating voltage ofthe data voltage Vd (ac)=±7 V is applied to the liquid crystal layer.

FIG. 21B shows the unevenness of display of the MVA-LCD fabricated bythis liquid crystal driving method. FIG. 21B shows a display state ofthree pixels arranged in order of G (Green) B (Blue) and R (Red) fromthe left. A dark portion X1 and a bright portion X2 shown in a verticalellipse in the drawing are seen. It is understood that as stated above,if polymer fixation is performed by the driving method shown in thegraph of FIG. 21A, the alignment of the liquid crystal in the pixel,especially the alignment state in the vicinity of a pixel edgefluctuates and the dark portion X1 is formed as shown in FIG. 21B.Besides, there arises a problem that when the whole display region ofthe panel in the state like this is observed, the display is seen to berough.

Besides, in the above liquid crystal driving method, the gate voltage Vgis made sufficiently larger than the voltage Vd (dc)+Vd (ac) of thedrain bus line to turn on the TFT, and then, the voltage Vd (dc)+Vd (ac)for tilting the liquid crystal molecules is applied to the drain busline. However, if polymerization is made in this driving state, a largefluctuation occurs in threshold values of the respective TFTs providedin the respective pixels, and there arises a defect that a desireddisplay can not be produced or the unevenness of display occurs sincesome TFT is not turned on in a portion on the display region of thecompleted LCD.

Besides, there is a case where an alignment regulating structural memberis provided to keep the liquid crystal in a desired alignmentorientation at the time of monomer polymerization. As the alignmentregulating structural member, there is, for example, a structure used ina subsequent embodiment and shown in FIG. 4A. In this structure, linearcruciform connection electrodes 12 and 14 dividing a rectangular pixelinto four rectangles of the same shape are formed. The connectionelectrode 12 is formed at the substantially center portion of therectangular pixel and parallel with a long side, and the connectionelectrode 14 is formed on a storage capacitance bus line 18 crossing thesubstantially center portion in the pixel.

A plurality of stripe-like electrodes 8 of a minute electrode patternare formed to be repeatedly extended from the connection electrodes 12and 14 at an angle of 45°. A pixel electrode is constituted by theconnection electrodes 12 and 14 and the plurality of stripe-likeelectrodes 8. A space 10 in a state in which a portion of an electrodeis cut away is formed between the adjacent stripe-like electrodes 8. Thestripe-like electrode 8 and the space 10 constitute an alignmentregulating structural member. Incidentally, instead of the stripe-likeelectrode 8 and the space 10 of FIG. 4A, a minute linear protrusion maybe naturally formed on a pixel electrode formed on the whole surface ina pixel.

When such a minute line and space pattern is formed, liquid crystalmolecules are aligned in parallel with the longitudinal direction of theminute pattern. By doing so, alignment division boundary portions in thepixel can be made as small as possible. However, there arises a problemthat T-V characteristics (transmissivity—gradation voltagecharacteristics) are changed by slight fluctuation of the width of theminute electrode pattern due to fluctuation of an exposure pattern in aphotolithography process, and this is seen as the unevenness of display.

Besides, as described above, since a rubbing processing is not performedto the alignment film in the MVA-LCD, means for regulating the alignmentorientation with respect to liquid crystal molecules in the outsideregion of the pixel electrode is not provided. Thus, as shown in FIG.20A, there is a case where singular points (indicated by ∘ or  in thedrawing) of alignment vectors are generated outside the pixel electrodeat random, and the alignment is maintained as it is. Thus, if monomersare polymerized in a state where liquid crystal molecules 24 a outsidethe pixel electrode or in the vicinity of an edge of the pixel electrodeare aligned in an orientation other than a desired one, as shown in FIG.20A, a dark line is formed in a region connecting the adjacent singularpoints, and there arises a problem that the luminance is lowered, aresponse time becomes long, or the unevenness of display occurs.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystaldisplay in which an alignment orientation of a liquid crystal isregulated by using a polymer fixation method so that a wide angle ofview can be obtained and a response time at a halftone can be shortened,and a method of manufacturing the same.

The above object can be achieved by a method of manufacturing a liquidcrystal display having n-channel TFTs, which comprises steps of sealinga liquid crystal layer containing a polymerizable component, which ispolymerized by light or heat, between substrates, and polymerizing thepolymerizable component while a voltage is applied to the liquid crystallayer to regulate a pretilt angle of a liquid crystal molecule and/or atilt direction at a time of driving, and is characterized in that thevoltage is applied to the liquid crystal layer under a voltageapplication condition 2 subsequently to a voltage application condition1 mentioned below, and the polymerizable component is polymerized at astage of the voltage application condition 2;

voltage application condition 1: Vg>Vd(dc)=Vc, and

voltage application condition 2: Vc>Vd (dc),

where,

Vg: applied voltage to a gate bus line,

Vc: applied voltage to a common electrode, and

Vd (dc): applied voltage (direct-current component) to a drain bus line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are views for explaining a first principle of a liquidcrystal display and a method of manufacturing the same according to afirst embodiment of the present invention;

FIGS. 2A and 2B are views for explaining a second principle of theliquid crystal display and the method of manufacturing the sameaccording to the first embodiment of the present invention;

FIGS. 3A and 3B are views for explaining a third principle of the liquidcrystal display and the method of manufacturing the same according tothe first embodiment of the present invention;

FIGS. 4A and 4B are views for explaining a fourth principle of theliquid crystal display and the method of manufacturing the sameaccording to the first embodiment of the present invention;

FIG. 5 is a view for explaining the fourth principle of the liquidcrystal display and the method of manufacturing the same according tothe first embodiment of the present invention;

FIG. 6 is a view for explaining a fifth principle of the liquid crystaldisplay and the method of manufacturing the same according to the firstembodiment of the present invention;

FIGS. 7A and 7B are views for explaining a comparative example 1-1 ofthe first embodiment of the present invention;

FIG. 8 is a view showing results of alignment states in pixels androughness of display of LCDs obtained in examples 1-1 and 1-2 of thefirst embodiment of the present invention and comparative examples 1-1and 1-2;

FIGS. 9A to 9F are views showing the change of liquid crystal alignmentstates resulting from the level change of a gate voltage Vg;

FIG. 10 is a view showing the relation between the alignment state andthe unevenness due to the threshold shift of TFTs with respect to gatevoltage Vg;

FIGS. 11A and 11B are views showing results of a simulation showing therate of change of transmissivity at a halftone display in a case where awidth L of a stripe-like electrode 8 is formed to be shifted from adesign value by about 0.2 μm in example 1-5 according to the firstembodiment of the present invention;

FIGS. 12A and 12B are views showing actually measured values of the rateof change of transmissivity at a halftone display in a case where thewidth L of the stripe-like electrode 8 is formed to be shifted from thedesign value by about 0.2 μm in the example 1-5 according to the firstembodiment of the present invention;

FIGS. 13A and 13B are views showing actually measured values of the rateof change of transmissivity at a halftone display in a case where thewidth L of the stripe-like electrode 8 is formed to be shifted from thedesign value by about 0.2 μm in the example 1-5 according to the firstembodiment of the present invention;

FIGS. 14A and 14B are views showing actually measured values of the rateof change of transmissivity at a halftone display in a case where thewidth L of the stripe-like electrode 8 is formed to be shifted from thedesign value by about 0.2 μm in the example 1-5 according to the firstembodiment of the present invention;

FIG. 15 is a view for explaining example 1-6 of the liquid crystaldisplay and the method of manufacturing the same according to the firstembodiment of the present invention;

FIG. 16 is a view for explaining example 1-7 of the liquid crystaldisplay and the method of manufacturing the same according to the firstembodiment of the present invention;

FIG. 17 is a view for explaining the example 1-7 of the liquid crystaldisplay and the method of manufacturing the same according to the firstembodiment of the present invention;

FIG. 18 is a view for explaining example 1-9 of the liquid crystaldisplay and the method of manufacturing the same according to the firstembodiment of the present invention;

FIGS. 19A and 19B are views for explaining the example 1-9 of the liquidcrystal display and the method of manufacturing the same according tothe first embodiment of the present invention;

FIGS. 20A and 20B are views showing singular points of alignmentvectors;

FIGS. 21A and 21B are views showing a liquid crystal driving method atthe time of forming a polymer (polymerization) in a conventional MVA-LCDto which an alignment fixation processing by a polymer fixation systemis performed;

FIGS. 22A and 22B are views showing an MVA-LCD having a half dividedalignment region, wherein FIG. 22A shows a state in which one pixel 2 ofthe MVA-LCD is viewed in the direction of a normal of a substrate, andFIG. 22B shows a section obtained by cutting the MVA-LCD shown in FIG.22A along a line parallel with a drain bus line 6;

FIG. 23 is a microscopic observation view of a pixel;

FIG. 24 is a view in which one pixel 2 of an MVA-LCD of example 2-1according to a second embodiment of the present invention is viewed inthe direction of a normal of a substrate surface;

FIG. 25 is a view showing a sectional shape taken along line D-D of FIG.24;

FIG. 26 is a view showing a modified example of the example 2-1according to the second embodiment of the present invention;

FIG. 27 is a T-V diagram showing the effect of the example 2-1 accordingto the second embodiment of the present invention;

FIG. 28 is a view in which one pixel 2 of an MVA-LCD of example 2-2according to the second embodiment of the present invention is viewed inthe direction of a normal of a substrate surface;

FIG. 29 is a view showing a sectional shape taken along line E-E of FIG.28;

FIG. 30 is a view showing a modified example of the example 2-2according to the second embodiment of the present invention;

FIG. 31 is a T-V diagram showing the effect of the example 2-2 accordingto the second embodiment of the present invention;

FIG. 32 is a view in which one pixel 2 of an MVA-LCD of example 2-3according to the second embodiment of the present invention is viewed inthe direction of a normal of a substrate surface;

FIG. 33 is a view showing an arrangement position of an electric fieldshielding electrode 70 of the MVA-LCD according to the second embodimentof the present invention and its operation;

FIG. 34 is a T-V diagram showing the effect of the example 2-3 accordingto the second embodiment of the present invention;

FIG. 35 is a view in which one pixel 2 of an MVA-LCD of example 2-4according to the second embodiment of the present invention is viewed inthe direction of a normal of a substrate surface;

FIG. 36 is a T-V diagram showing the effect of the example 2-4 accordingto the second embodiment of the present invention;

FIG. 37 is a view in which one pixel 2 of an MVA-LCD of example 2-5according to the second embodiment of the present invention is viewed inthe direction of a normal of a substrate surface;

FIG. 38 shows a construction in which a gap 76 between a drain bus line6 and a pixel electrode 3 is wide in the example 2-5 according to thesecond embodiment of the present invention;

FIG. 39 is a view showing that in the example 2-5 according to thesecond embodiment of the present invention, the electric field shieldingelectrode 70 of the example 2-3 is provided in an under layer of the gap76;

FIG. 40 is a T-V diagram showing the effect of the example 2-5 accordingto the second embodiment of the present invention;

FIG. 41 is a view in which one pixel 2 of an MVA-LCD of example 2-6according to the second embodiment of the present invention is viewed inthe direction of a normal of a substrate surface;

FIG. 42 is a view showing a section taken along line F-F of FIG. 41;

FIG. 43 is a view showing a section taken along line G-G of FIG. 41;

FIG. 44 is a view showing the direction of rubbing in the example 2-6according to the second embodiment of the present invention;

FIG. 45 is a T-V diagram showing the effect of the example 2-6 accordingto the second embodiment of the present invention;

FIGS. 46A to 46E are views for explaining a tilting operation of aliquid crystal molecule 24 a according to a third embodiment of thepresent invention;

FIG. 47 is a view showing an example in which a connection electrode 64is provided at the center of a pixel in example 3-1 of the thirdembodiment of the present invention;

FIG. 48 is a view showing an example in which the connection electrode64 is provided on the side of a gate bus line 4 in the example 3-1 ofthe third embodiment of the present invention;

FIG. 49 is a view showing a conventional MVA-LCD;

FIG. 50 is a view showing a tilt direction and a tilt angle θp of aliquid crystal molecule 24 a;

FIG. 51 is a view showing the arrangement relation of arrangementregions 80 according to a fourth embodiment of the present invention;

FIG. 52 is a view showing a directional structural member or a surfacereformed region according to the fourth embodiment of the presentinvention;

FIG. 53 is a view showing another example of the directional structuralmember or the surface reformed region according to the fourth embodimentof the present invention;

FIGS. 54A to 54F are views each showing still another example of thedirectional structural member or the surface reformed region accordingto the fourth embodiment of the present invention;

FIG. 55 is a view showing a construction for improving a visual angleproperty of an LCD according to the fourth embodiment of the presentinvention;

FIG. 56 is a view showing an arrangement example of a structural memberaccording to the fourth embodiment of the present invention;

FIG. 57 is a view showing another example of the arrangement example ofthe structural member according to the fourth embodiment of the presentinvention;

FIG. 58 is a view showing still another example of the arrangementexample of the structural member according to the fourth embodiment ofthe present invention;

FIG. 59 is a view showing a boundary structural member according to thefourth embodiment of the present invention;

FIG. 60 is a view showing another example of the boundary structuralmember according to the fourth embodiment of the present invention;

FIG. 61 is a view showing a specific shape of the boundary structuralmember according to the fourth embodiment of the present invention;

FIG. 62 is a view showing another specific shape of the boundarystructural member according to the fourth embodiment of the presentinvention;

FIG. 63 is a view showing a state in which three adjacent pixels 2 of anLCD according to a fifth embodiment of the present invention are viewedin the direction of a normal of a substrate surface;

FIG. 64 is a view showing a state in which three adjacent pixels 2 of anLCD in an example according to the fifth embodiment of the presentinvention are viewed in the direction of a normal of a substratesurface.

FIG. 65 is a view showing a modified example of the example according tothe fifth embodiment of the present invention;

FIG. 66 is a view showing a basic construction of an LCD using a polymerfixation system;

FIGS. 67A and 67B are views showing a conventional system in whichvoltage is applied to a liquid crystal layer 24 when monomer material isirradiated with UV and is polymerized;

FIGS. 68A and 68B are views in which an example according to a sixthembodiment of the present invention is compared with a conventionalexample;

FIG. 69 is a view showing a liquid crystal display according to aseventh embodiment of the present invention and a method ofmanufacturing the same;

FIGS. 70A and 70B are views for explaining a problem in a case wherealignment regulating force is increased by the polymer fixation system;

FIG. 71 is a view showing a driving waveform of a liquid crystal displayof example 8-1 according to an eighth embodiment of the presentinvention;

FIGS. 72A and 72B are views showing a state in which two adjacent pixels2 are viewed in the direction of a normal of a substrate surface in theliquid crystal display of the example 8-1 according to the eighthembodiment of the present invention;

FIG. 73 is a view showing a driving waveform of a liquid crystal displayof example 8-2 according to the eighth embodiment of the presentinvention;

FIG. 74 is a view showing a driving waveform of a conventional liquidcrystal display as a comparative example;

FIG. 75 is a view for explaining an effect of the eighth embodiment ofthe present invention;

FIG. 76 is a view showing a schematic construction of a liquid crystaldisplay using an alignment fixing technique;

FIG. 77 is a view for explaining a problem in a case where a sealingagent made of a photo-curing resin is used for a liquid crystalinjection port, which is used in a conventional dip injection method;

FIG. 78 is a view for explaining a problem in a case of using a mainseal made of a photo-curing resin used in a conventional droppinginjection method;

FIG. 79 is a view showing results of measurement of a light absorptionspectrum of a liquid crystal composite in example 9-1 of a ninthembodiment of the present invention;

FIG. 80 is a view showing results of measurement of an absorptionspectrum of a resin used for a sealing agent 126;

FIG. 81 is a view showing results of measurement of a light absorptionspectrum of a sealing agent in example 9-3 of the ninth embodiment ofthe present invention;

FIGS. 82A and 82B are views showing a light shielding structural member130 in example 9-4 of the ninth embodiment of the present invention;

FIG. 83 is a view showing a light attenuation structural member 132 inexample 9-5 of the ninth embodiment of the present invention;

FIG. 84 is a view showing the rate of change of transmissivity of anon-polymer-fixed panel and the rate of change of transmissivity of apolymer-fixed panel by comparison;

FIG. 85 is a view showing the relation of the attained transmissivityand the rising time with respect to an LCD having a liquid crystal whichis not polymer fixed and an LCD having a liquid crystal which is polymerfixed in the first embodiment of the present invention; and

FIG. 86 is a view showing the relation of the gradation and the risingtime with respect to an LCD having a liquid crystal which is not polymerfixed and an LCD having a liquid crystal which is polymer fixed in thefourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A liquid crystal display according to a first embodiment of the presentinvention and a method of manufacturing the same will be described withreference to FIGS. 1A to 21B. First, a first principle of the liquidcrystal display and the method of manufacturing the same according tothis embodiment will be described with reference to FIGS. 1A and 1B.FIG. 1A shows a liquid crystal driving method according to the firstprinciple at the time of polymer polymerization in an MVA-LCD to whichan alignment fixation processing by a polymer fixation system isperformed. FIG. 1B shows a display state of the MVA-LCD in which apolymer formed by the liquid crystal driving method of the firstprinciple shown in FIG. 1A exists in a liquid crystal layer. Then-channel type TFTs are used in this MVA-LCD.

In a polymerization step of a manufacturing stage of an LCD, the liquidcrystal driving method according to the first principle is based ondirect-current voltage driving, and an alternating voltage is notapplied to the liquid crystal layer. Further, a voltage sufficientlyhigher than that of a drain (data) bus line is applied to a gate busline, and a voltage of a common electrode is made higher than thevoltage of the drain bus line (pixel electrode). By doing so, ascompared with the conventional example shown in FIGS. 21A and 21B, thereis no disturbance of a liquid crystal alignment in a pixel and it ispossible to obtain a display having no roughness even when the wholepanel is viewed.

For example, as shown in a graph of FIG. 1A, a gate voltage Vg=33 V iskept applied to all gate bus lines of a panel display region, a TFTprovided for each pixel is kept turned on, and a direct-current datavoltage Vd (dc)=13 V is applied to all drain bus lines. By this, Vd (dc)is written to a pixel electrode formed in each pixel region. On theother hand, a common electrode arranged opposite to the pixel electrodeacross the liquid crystal layer is kept at a common voltage Vc=20 V. Bythis, a direct-current voltage of −7V with respect to the commonpotential is applied to the liquid crystal layer.

A display of the MVA-LCD fabricated by this liquid crystal drivingmethod is shown in FIG. 1B. FIG. 1B shows a display state of threepixels arranged in order of G (Green), B (Blue) and R (Red) from theleft. It is understood that if polymer fixation is performed by thedriving method shown in the graph of FIG. 1A, as shown in FIG. 1B, thefluctuation of the liquid crystal alignment in the pixel, especially thefluctuation of the alignment state in the vicinity of a pixel edgedisappears, and the dark portion X1 of FIG. 21B disappears. By this,unevenness of display disappears, and even when the whole display regionof the panel is observed, roughness of display is not seen.

Next, a second principle of the liquid crystal display and the method ofmanufacturing the same according to this embodiment will be describedwith reference to FIGS. 2A and 2B. FIG. 2A shows a liquid crystaldriving method according to the second principle. FIG. 2B shows adisplay state of an MVA-LCD in which a polymer formed by the liquidcrystal driving method of the second principle shown in FIG. 2A existsin a liquid crystal layer.

In a polymerization step of monomers in the liquid crystal layer sealedbetween substrates, according to a liquid crystal driving method of thesecond principle, a voltage sufficiently higher than that of a drain busline is applied to a gate bus line, and a voltage of a common electrodeis made higher than the voltage of the drain bus line (pixel electrode).Thereafter, while the potential of the common electrode is made toapproach the voltage of the pixel electrode, an alternating voltage issimultaneously applied to the pixel electrode. The direct-currentvoltage is first applied to the liquid crystal layer, and thereafter,the alternating voltage is applied. Also in this case, as compared withthe conventional example of FIGS. 21A and 21B, there is no disturbanceof a liquid crystal alignment in a pixel, and a display withoutroughness can be obtained even when the whole panel is viewed.

For example, as shown by a graph at the upper side of FIG. 2A, a gatevoltage Vg=33 V is kept applied to all gate bus lines of a panel displayregion, a TFT provided in each pixel is kept turned on, and adirect-current data voltage Vd (dc)=13V is applied to all drain buslines. By this, Vd (dc) is written to the pixel electrode formed in eachpixel region. On the other hand, the common electrode arranged oppositeto the pixel electrode across the liquid crystal layer is kept at acommon voltage Vc=20 V. By this, a direct-current voltage of −7 V withrespect to the common potential is applied to the liquid crystal layer.

Next, as shown by a graph at the lower side of FIG. 2A, the commonvoltage Vc is made to gradually approach the data voltage Vd (dc)=13 Vfrom 20 V. At the same time, an alternating data voltage Vd (ac) issuperimposed on the direct-current data voltage Vd (dc)=13 V while itslevel is gradually increased to ±7 V. By this, Vd (dc)+Vd (ac) iswritten to the pixel electrode formed in each pixel region. Thedirect-current voltage is first applied to the liquid crystal layer, andthen, the alternating voltage is applied.

A display of the MVA-LCD fabricated by this liquid crystal drivingmethod is shown in FIG. 2B. FIG. 2B shows a display state of threepixels having a similar construction to FIG. 1B. When the polymerfixation is performed by the driving method shown in the graph of FIG.2A, as shown in FIG. 2B, although a slight fluctuation occurs in analignment state in the vicinity of a pixel edge, a dark portion X1 ofFIG. 2B is smaller than the dark portion X1 of FIG. 21B, and thefluctuation of luminance is decreased. By this, unevenness of displaycan be reduced, and roughness of display can be reduced even when thewhole display region of the panel is observed.

Next, a third principle of the liquid crystal display and the method ofmanufacturing the same according to this embodiment will be describedwith reference to FIGS. 3A and 3B. FIG. 3A shows the third principle inwhich another driving method is added to the liquid crystal drivingmethod according to the first principle, and FIG. 3B shows the thirdprinciple in which another driving method is added to the liquid crystaldriving method according to the second principle.

Left graphs of FIGS. 3A and 3B respectively show the driving methods ofthe first and second principles shown in FIGS. 1A and 1B and FIGS. 2Aand 2B. Subsequently to the liquid crystal driving by these drivingmethods, the applied voltage Vg to the gate bus line is graduallylowered as indicated by an arrow in the drawing and is made to approachthe applied voltage (data voltage Vd (dc)+Vd (ac)) to the drain bus line(see the center and right graphs in the drawing). By polymerizingmonomers in this state, it is possible to suppress the fluctuation ofthreshold values of TFTs and to obtain a panel in which unevenness ofdisplay does not occur.

Next, a fourth principle of the liquid crystal display and the method ofmanufacturing the same according to this embodiment will be describedwith reference to FIGS. 4A to 5. FIG. 4A shows one pixel 2 viewed in thedirection of a normal of a substrate surface. Since FIG. 4A is alreadyexplained in the section of describing the related art, the explanationis omitted. FIG. 4B shows a partial section taken along line A-A of FIG.4A. FIG. 5 shows a partial section taken along line B-B of FIG. 4A.

In FIGS. 4B and 5, a drain bus line 6 is formed on a glass substrate 20on the side of an array substrate, and an insulating film 22 is formedthereon. A pixel electrode is formed on the insulating film 22 byconnection electrodes 12 and 14 and a plurality of stripe-likeelectrodes 8. An alignment film 32 in contact with a liquid crystallayer 24 is formed on the pixel electrode. An opposite substrate isarranged opposite to the glass substrate 20 across the liquid crystallayer 24. A color filter layer 28 is formed on a glass substrate 30 onthe side of the opposite substrate, and a common electrode 26 is formedthereon. An alignment film 34 is formed on the common electrode 26 andis in contact with the liquid crystal layer 24. The thickness of theliquid crystal layer 24 is regulated to a predetermined cell gap d. Asshown in FIG. 5, a liquid crystal molecule 24 a is aligned in parallelwith an extension direction of the stripe-like electrode 8 by alignmentregulation caused by the stripe-like electrode 8 and the space 10.

In the fourth principle, an electrode width L of the stripe-likeelectrode 8 shown in FIGS. 4A and 5 is made larger than a width S of thespace 10. By doing so, the change of transmissivity with respect to apattern fluctuation occurring at the time of patterning process(exposure, development, etching) of the stripe-like electrode 8 isdecreased, and the unevenness of display can be improved.

Next, a fifth principle of the liquid crystal display and the method ofmanufacturing the same according to this embodiment will be describedwith reference to FIG. 6. FIG. 6 shows a construction of one pixelviewed in the direction of a normal of a substrate surface. By changingthe width of a bus line (in this example, the width of a drain bus line)in the extension direction, a control can be made so that occurrencepositions of singular points (indicated by ∘ or  in the drawing) ofalignment vectors become definite positions. That is, the bus line ismade an alignment regulating structure, and the singular points of thealignment vectors of liquid crystal molecules outside the pixelelectrode can be formed at the definite positions. By this, since thealignment of liquid crystal outside the pixel electrode become fixed,monomers are polymerized while occurrence of a dark line as shown inFIG. 20A is suppressed, and the luminance and the unevenness of displaycan be improved.

The liquid crystal display according to this embodiment using the abovefirst to fifth principles and the method of manufacturing the same willbe specifically described using examples and comparative examples.

Example 1-1

This example will be described using FIGS. 1A and 1B and FIGS. 4A and 4Bagain. In this example, an XGA panel (pixel pitch was 297 μm, and thenumber of pixels was 1024×768) having a size of 15 inches in diagonalwas fabricated. The pixel structure of the panel is shown in FIGS. 4Aand 4B. An n-channel TFT 16, a drain bus line 6, a gate bus line 4, anda pixel electrode formed of connection electrodes 12 and 14 and aplurality of stripe-like electrodes 8 were formed on an array substrateincluding a glass substrate 20. A color filter layer 28 and a commonelectrode 26 were formed on an opposite substrate including a glasssubstrate 30. A glass substrate having a thickness of 0.7 mm was used asa substrate material. The plurality of stripe-like electrodes 8 wereformed to extend in four directions (upper right, lower right, upperleft, lower left) from the center portion of the pixel, respectively.The electrode width of the stripe-like electrode 8 was made 3 μm, andthe width of the space 10 was made 3 μm. Vertically aligned films(polyimide material) were formed on these substrates by using a printingmethod, and a heat treatment at 180° C. for 60 minutes was carried out.These substrates were bonded to each other through a spacer of adiameter of 4 μm, and an empty cell (a cell in a state where liquidcrystal is not injected) was fabricated. A liquid crystal having anegative dielectric anisotropy added with a trace amount ofphotopolymerization monomer was injected into the thus obtained cell,and a liquid crystal panel was fabricated. The addition amount of thephotopolymerization monomer was made 2.4 wt %.

Next, ultraviolet (UV) light was irradiated to the liquid crystal layer24 in a state where a voltage was applied, and the photo-polymerizablemonomer was polymerized. As shown in FIGS. 3A and 3B as well, thedriving voltage was applied to the liquid crystal layer 24 under avoltage application condition 2 subsequently to a voltage applicationcondition 1 mentioned below, and light irradiation to the liquid crystallayer 24 was performed at the stage of the voltage application condition2;

voltage application condition 1: Vg=33 V, Vc=Vd(dc)=13 V, andvoltage application condition 2: Vg=33 V, Vc=20 V, Vd(dc)=13 V.

The procedure of the voltage application will be described moreparticularly. First, the gate voltage Vg was made Vg=Vc=Vd (dc)=13 V.Next, the gate voltage Vg was raised up to 33 V. The speed of a voltagerise was made about 1 V/sec. Next, the common voltage Vc was raised upto 20 V. The speed of a voltage rise was made about 1 V/sec. Especially,it is preferable that this voltage rise is a continuous change, and ifthe voltage is abruptly raised, there is a case where a disturbance ofalignment occurs in a pixel. Incidentally, in this example, although thecommon voltage Vc was raised up to 20 V, since it is sufficient if thecommon voltage Vc>the data voltage Vd (dc) is satisfied, for example,the data voltage Vd (dc) may be dropped without changing the commonvoltage Vc.

The amount of light irradiation for polymerization was made about 2000mJ/cm² (wavelength λ=365 nm). There was no disturbance in the alignmentstate in the pixel, and a display having no feeling of roughness wasobtained. Incidentally, when the voltage is changed from the drivingcondition 1 to the driving condition 2, if the common voltage Vc is oncemade higher than a predetermined value and is dropped, the feeling ofroughness is further improved. For example, it is appropriate that thecommon voltage is raised from Vc=13 V to Vc=23 V, and then is dropped toVc=20 V.

Comparative Example 1-1

A comparative example will be described with reference to FIGS. 7A and7B. This comparative example is the same as the example 1-1 except forthe following requirements. The driving voltage was applied to theliquid crystal layer 24 under a voltage application condition 2subsequently to a voltage application condition 1 mentioned below, andlight irradiation to the liquid crystal layer 24 was performed at thestage of the voltage application condition 2;

voltage application condition 1: Vg=33 V, Vc=Vd(dc)=13 V, andvoltage application condition 2: Vg=33 V, Vc=6 V, Vd(dc)=13 V.

As compared with the example 1-1, in this comparative example, themagnitude relation of the common voltage Vc and the data voltage Vd (dc)is reversed. In the case of this comparative example, the alignment inthe pixel was greatly disturbed, and roughness was seen on the display.

Comparative Example 1-2

This comparative example will be described with reference to FIGS. 21Aand 21B. This comparative example is the same as the example 1-1 exceptfor the following requirements. The driving voltage was applied to theliquid crystal layer 24 under a voltage application condition 2subsequently to a voltage application condition 1 mentioned below, andlight irradiation to the liquid crystal layer 24 was performed at thestage of the voltage application condition 2;

voltage application condition 1: Vg=33 V, Vc=Vd(dc)=13 V, andvoltage application condition 2: Vg=33 V, Vc=13 V, Vd(dc)=13 V, Vd(ac)=7V(rectangular wave of 30 Hz).

The alternating voltage is applied to the pixel electrode, and thisdriving method is closest to an actual liquid crystal driving system ofan LCD. However, in this case, there was a disturbance in the alignmentin the vicinity of a pixel edge portion and roughness was seen on thedisplay.

Example 1-2

This example will be described with reference to FIGS. 2A and 2B. Thisexample is the same as the example 1-1 except for the followingrequirements. The driving voltage was applied to the liquid crystallayer 24 under a voltage application condition 2 subsequently to avoltage application condition 1 mentioned below, and the driving voltagewas further applied under a voltage application condition 3, and lightirradiation to the liquid crystal layer 24 was performed at the stage ofthe voltage application condition 3;

voltage application condition 1: Vg=33 V, Vc=Vd(dc)=13 V,voltage application condition 2: Vg=33 V, Vc=20 V, Vd(dc)=13 V, andvoltage application condition 3: Vg=33 V, Vc=Vd(dc)=13 V, Vd(ac)=7 V(30Hz).

After the liquid crystal driving similar to the example 1-1, while thecommon voltage Vc was made to gradually approach the value of the datavoltage Vd (dc), the amplitude of the data voltage Vd (ac) was graduallyincreased. By this, in this example, although the alignment of a pixeledge was slightly disturbed, a display without the feeling of roughnesswas obtained.

FIG. 8 shows results of alignment states in pixels and roughness ofdisplay of LCDs obtained in the examples 1-1, 1-2 and the comparativeexamples 1-1 and 1-2. In the drawing, ∘ denotes “good”, Δ denotes“acceptable”, and x denotes “inferior”.

Example 1-3

Next, this example will be described with reference to FIG. 3A. Thisexample is the same as the example 1-1 except for the followingrequirements. The driving voltage was applied to the liquid crystallayer 24 under a voltage application condition 2 subsequently to avoltage application condition 1 mentioned below, and was further appliedunder a voltage application condition 3, and light irradiation forpolymerization of a photo-polymerizable monomer was performed to theliquid crystal layer 24 at the stage of the voltage applicationcondition 3;

voltage application condition 1: Vg=33 V, Vc=Vd(dc)=13 V,voltage application condition 2: Vg=33 V, Vc=20 V, Vd(dc)=13 V, andvoltage application condition 3: Vg=13 V, Vc=20 V, Vd(dc)=13 V.

That is, after the liquid crystal driving similar to the example 1-1 wasperformed, the level of the gate voltage Vg was gradually lowered andwas made equal to the data voltage Vd (dc).

By doing so, in the case where UV irradiation was performed to theliquid crystal layer 24 by only the driving of the example 1-1, therewas a case where unevenness of display caused by the thresholdfluctuation of TFTs occurred, however, in the case where the liquidcrystal driving as described in this example was made, the unevenness ofdisplay caused by the threshold fluctuation of the TFTs was completelyeliminated, and the liquid crystal alignment in the pixel was almostexcellent.

FIGS. 9A to 9F show the change of liquid crystal alignment statesresulting from the level change of the gate voltage Vg. FIGS. 9A to 9Fshow display states in which the gate voltages Vg are 33 V, 26 V, 20 V,13 V, 10 V, and 6 V. FIG. 9A shows the same state as FIG. 1B. As shownin FIGS. 9B to 9D, the alignment state is almost stable up to the gatevoltage Vg=Vd (dc)=13 V. As shown in FIGS. 9E and 9F, when the gatevoltage becomes Vg<Vd (dc), a noticeable dark line appears in thevicinity of the gate bus line. Accordingly, if a polymer is formed inthe state of the gate voltage Vg<Vd (dc), although the unevenness ofdisplay or the roughness caused by the threshold shift of the TFTs doesnot occur, the display luminance is lowered.

Next, FIG. 10 shows the relation between the alignment state and theroughness caused by the threshold shift of the TFTs with respect to thegate voltage Vg. As shown in FIG. 10, it can be said that in the liquidcrystal panel used in this example, the gate voltage Vg=13 to 20 V isthe optimum driving condition. Especially, the gate voltage Vg=13 V hasthe same value as the data voltage Vd (dc), and the potentialdistribution on the array substrate on which the TFTs are formed can bemade flat. Accordingly, since the influence of an unnecessary horizontalelectric field is reduced at the pixel electrode edge, the disturbanceof alignment can not be occurred, and it can be said that the voltage isa preferable liquid crystal driving condition at the time ofpolymerization.

Example 1-4

Next, this example will be described with reference to FIG. 3B. Thisexample is the same as the example 1-1 except for the followingrequirements. The driving voltage was applied to the liquid crystallayer 24 under a voltage application condition 2 and a voltageapplication condition 3 in this sequence subsequently to a voltageapplication condition 1 mentioned below, and the driving voltage wasfurther applied thereto under a voltage application condition 4, andlight irradiation was performed to a photo-polymerizable monomer of theliquid crystal layer 24 at the stage of the voltage applicationcondition 4;

voltage application condition 1: Vg=33 V, Vc=Vd(dc)=13 V,voltage application condition 2: Vg=33 V, Vc=20 V, Vd(dc)=13 V,voltage application condition 3: Vg=33 V, Vc=Vd(dc)=13 V, Vd(ac)=7 V (30Hz), andvoltage application condition 4: Vg=13 V, Vc=Vd(dc)=13 V, Vd(ac)=7 V (30Hz).

That is, after the liquid crystal driving similar to the example 1-2 wasperformed, the level of the gate voltage Vg was gradually lowered andwas made equal to the data voltage Vd (dc).

By doing so, in the case where UV irradiation was performed to theliquid crystal layer 24 by only the driving of the example 1-1, therewas a case where unevenness of display caused by the thresholdfluctuation of TFTs occurred, however, in the case where the liquidcrystal driving as described in this example was performed, theunevenness of display caused by the threshold fluctuation of the TFTswas completely eliminated, and the liquid crystal alignment in the pixelwas almost excellent.

Example 1-5

This example will be described with reference to FIGS. 11A to 14B inaddition to FIGS. 4A to 5. This example is the same as the example 1-3except for the following requirements.

In this example, the pattern width L of the stripe-like electrode 8shown in FIGS. 4A, 4B and 5 is made larger than the space width S of thespace 10. Specifically, the widths are conventionally L=3 μm and S=3 μm,however, in this example, the widths are made L=4 μm and S=2 μm. FIGS.11A to 14B show the rate of change of transmissivity at a halftonedisplay in the case where the width L of the stripe-like electrode 8 isformed to be shifted from a design value by about 0.2 μm.

FIGS. 11A and 11B show results of a simulation, and FIGS. 12A to 14Bshow actually measured values obtained from actual liquid crystal cells.FIGS. 12A and 12B show the values of liquid crystal panels having a cellgap d=4 μm, FIGS. 13A and 13B show the values of liquid crystal panelshaving a cell gap d=3.5 μm, and FIGS. 14A and 14B show the values ofliquid crystal panels having a cell gap d=4.5 μm. FIGS. 11A to 14A showthe rate of change of transmissivity in the case where the pattern widthL (design value) of the stripe-like electrode 8 is taken in thehorizontal direction, the space width S (design value) is taken in thevertical direction, and the driving voltage of 3 V is applied to theliquid crystal layer 24. In FIG. 11A, the pattern width L=1 μm to 5 μmis divided at intervals of 0.5 μm, and the space width S=1 μm to 5 μm isdivided at intervals of 0.5 μm. In FIGS. 12A to 14B, the pattern widthL=2 μm to 5 μm is divided at intervals of 1 μm, and the space width S=1μm to 5 μm is divided at intervals of 1 μm.

A description will be given while the rate of change of transmissivityat L=3 and S=3 of FIG. 11A is cited as an example. For example, it isassumed that transmissivity is A % in the case where a driving voltageof 3 V is applied to a liquid crystal layer of a liquid crystal panelof, for example, L=3 μm (design value) and S=3 μm (design value). On theother hand, it is assumed that transmissivity is B % in the case where adriving voltage of 3 V is applied to a liquid crystal layer of a liquidcrystal panel in which the stripe-like electrode 8 has the width L=2.8μm shifted from the design value by 0.2 μm, and consequently the space10 has the width S=3.2 μm increased by 0.2 μm. Besides, transmissivityis made C % in the case where a driving voltage of 3 V is applied to aliquid crystal layer of a liquid crystal panel having L=3.2 μm and S=2.8μm.

The rate of change of transmissivity at L=3 and S=3 of FIG. 11A isexpressed by ((|A−B|/A+|A−C|/A)/2)×100(%), and in this example, it is14.17. The same applies to the other drawings of FIGS. 11A to 14A. FIGS.11B to 14B show graphs in which the horizontal axis indicates the widthL of the stripe-like electrode 8, and the vertical axis indicates thespace width S of the space 10, and the values of the respective drawingsA are plotted. As is apparent from FIGS. 11B to 14B, it is understoodthat in any cases, by making the pattern width L of the stripe-likeelectrode 8 larger than the space width S of the space 10, the rate ofchange of transmissivity becomes small. Besides, when results of theother conditions described here are considered together, it isunderstood that if the pattern width L is made large and the space widthS is made small, the rate of change is improved.

Incidentally, FIGS. 11A to 14B show the data of the rate of change oftransmissivity in the case where polymer fixed liquid crystal is notused.

From the experimental results, it is understood that even in the liquidcrystal panels using the same minute pattern electrodes, the tendency ofthe rate of change of transmissivity with respect to the pattern changeis slightly different between the LCD using the polymer fixed liquidcrystal and the LCD not using the polymer fixed liquid crystal.

FIG. 84 shows the rate of change of transmissivity of thenon-polymer-fixed panel and the rate of change of transmissivity of thepolymer-fixed panel by comparison. FIG. 84 shows the rate of change oftransmissivity of the non-polymer-fixed panel, and its left column showsrespective graphs in the case where the applied voltage is 2.5 V, 3 V,and 10 V in order from the above. Besides, correspondingly to the leftcolumn, the right column shows graphs concerning the rate of change oftransmissivity of the polymer-fixed panel (polymerization voltage=10 V),in the case where the applied voltage is 2.5 V, 3 V, and 10 V in orderfrom the above.

As is apparent from FIG. 84, the values of the space width S at whichthe rate of change becomes minimum at a halftone display are differentfrom each other. In the case where the polymer fixed liquid crystal isnot used, as the space width S becomes small, the rate of change becomessmall, however, in the case where the polymer fixed liquid crystal isused, the rate of change in the vicinity of the space width S=3.25 μm isminimum, and it is preferable that the space width S is S=2.5 μm ormore.

It is conceivable that the cause is that the alignment state obtained byvoltage application (here, application of 10 V) at the time ofpolymerization of monomer material exerts an influence upon thealignment state after the polymerization. The last line of FIG. 84 showsgraphs of the rate of change of transmissivity at the time ofapplication of 10 V. Contrary to the tendency at the halftone, when thepattern width L is large and the space width S is small, the rate ofchange is large. It is conceivable that since monomers are polymerizedin this state, the influence of the alignment state at the time ofpolymerization appears on the display at the halftone or the like afterthe polymerization.

Incidentally, at the time of the halftone display, the tendency that therate of change becomes large when the space width S is larger than thepattern width L is common to both. Besides, as typified by the casewhere the minute electrode pattern as described above is used, in themode where the alignment state at the time of driving is unstable if itremains unchanged, speeding-up by polymer fixation is further effective.FIG. 85 shows, in the mode including the stripe-like electrode asmentioned above, the relation between the attained transmissivity andthe rising time in an LCD including a polymer unfixed liquid crystal andan LCD including a polymer fixed liquid crystal. As shown in FIG. 85, inthe case where polymer fixation is not performed, the alignment ofliquid crystal at the time of voltage application is greatly disturbed,and consequently, the response is very slow. However, since thealignment of the liquid crystal is determined by performing the polymerfixation, a great improvement of the response is realized.

Example 1-6

This example will be described with reference to FIG. 15. This exampleis the same as the example 1-5 except for the following requirements. Aliquid crystal panel shown in FIG. 15 includes a pixel electrode 40having a shape different from the pixel electrode shown in FIGS. 4A, 4Band 5. In the pixel electrode 40, an electrode cut region (space 10) isnot formed in a pixel region. Instead thereof, linear protrusions 42each made of a dielectric are formed on the pixel electrode 40correspondingly to the spaces 10 shown in FIGS. 4A and 4B. A verticalalignment film 32 is formed on the pixel electrode 40 and the linearprotrusions 42.

A width S of the linear protrusion 42 is made smaller than an electrodeexposure width L between the adjacent linear protrusions 42.Specifically, the widths are conventionally L=3 μm and S=3 μm, whereasthe widths are L=4 μm and S=2 μm in this example. Since the space 10shown in FIGS. 4A and 4B and the linear protrusion 42 have almostequivalent alignment regulating effects, also in this example, the rateof change of transmissivity can be made small through the same effect asthe example 1-5. Incidentally, photosensitive acryl resin was used asthe dielectric material, and the height H of the linear protrusion 42was made about 0.3 μm.

Example 1-7

This example will be described with reference to FIGS. 16 and 17. Thisexample is the same as the example 1-5 except for the followingrequirements. A liquid crystal panel shown in FIG. 16 includes a pixelelectrode 46 having a shape different from the pixel electrode shown inFIGS. 4A, 4B and 15. In the pixel electrode 46, an electrode cut region(space 10) is not formed in a pixel region. Instead thereof, linearprotrusions 44 each made of a dielectric are formed at a lower layer ofthe pixel electrode 46 correspondingly to the spaces 10 shown in FIGS.4A and 4B. Accordingly, the pixel electrode 46 has an electrodestructure including a conductive protrusion. A vertical alignment film32 is formed on the pixel electrode 46.

A width of the conductive protrusion was made L, a width of a conductivegroove between the adjacent conductive protrusions was made S, and thecase of L=3 μm and S=3 μm and the case of L=4 μm and S=2 μm werecompared with the simulation example in the case of the combination ofthe stripe-like electrode 8 and the space 10 shown in FIGS. 11A and 11Bof the example 1-5. FIG. 17 shows comparison results. As shown in FIG.17, it is understood that the change of transmissivity in the electrodestructure of the conductive protrusion is remarkably small, and thestructure is such that roughness caused by the fluctuation of thepattern is hard to produce.

Example 1-8

This example will be described using FIG. 6 again. This example is thesame as the example 1-5 except for the following requirements. As shownin FIG. 6, the width of a drain bus line 6 was continuously changed. Thewidth was made thin in the vicinity of an intersection of the drain busline 6 and a gate bus line 4, and was made thick in the vicinity of thecenter between the gate bus lines 4. The width of the thin portion wasmade 3 μm, and the width of the thick portion was made 15 μm. Since thedirectionality of the liquid crystal alignment on the drain bus line 6becomes stable, the luminance and the unevenness of display can beimproved.

Example 1-9

This example will be described with reference to FIGS. 18 to 19B. Thisexample is the same as the example 1-5 except for the followingrequirements. FIG. 18 shows a display state in the case where liquidcrystal molecules 24 a in a pixel are ideally aligned in the pixelincluding the pixel electrode of the combination of the stripe-likeelectrodes 8 and the spaces 10 shown in FIGS. 4A and 4B. As shown inFIG. 18, dark lines X1 appear on a gate bus line 4, a drain bus line 6,connection electrodes 12 and 14, and a storage capacitance bus line 18,and further, the dark line X1 also appears at the peripheral portion ofthe pixel electrode constituted by the stripe-like electrodes 8 and thespaces 10.

In FIG. 18, a “∘” mark 52 denotes a singular point (−1) of an alignmentvector, and a “” mark 50 denotes a singular point (+1) of an alignmentvector. Incidentally, in the state shown in the drawing, two polarizingplates bonded to both surfaces of the liquid crystal panel are arrangedin crossed Nicols, the directions of the polarization axes of those aredirections shown by cruciform arrows of FIG. 18, and are tilted by 45°with respect to the main alignment orientation of the liquid crystalmolecule on the display region.

On the other hand, in the construction of this example shown in FIGS.19A and 19B, an insulating layer 56 thicker than a conventional one wasformed. FIG. 19A shows a state viewed in the direction of a normal of asubstrate surface, and FIG. 19B shows a section on the side of an arraysubstrate taken along line C-C of FIG. 19A. As shown in FIGS. 19A and19B, the stripe-like electrodes 8 are formed on the insulating layer 56,and the ends are formed to partially overlap with the drain bus line 6when viewed in the direction of the normal of the substrate surface.Photosensitive acryl resin was used as the material of the insulatinglayer 56, and the film thickness was made 3 μm.

Incidentally, a color filter layer may be formed on the side of thearray substrate (CF on TFT structure), and the color filter layer may beused instead of the insulating layer 56. Besides, as shown in FIG. 19B,a thick insulating layer may be naturally formed by stacking a colorfilter layer 54 and the insulating layer 56 (in this case, the substratemay be flattened by the insulating layer 56). By adopting theconstruction of this example, the influence of an oblique electric fieldfrom the drain bus line 6 to the liquid crystal layer 24 becomes weak,and the liquid crystal molecules 24 a are aligned by receiving only theinfluence of the stripe-like electrodes 8 and the spaces 10. By this,each of the dark lines X1 on the gate bus line 4 and the drain bus line6 unites with each of the dark lines X1 of the peripheral portion of thepixel electrode constituted by the stripe-like electrodes 8 and thespaces 10 to form only one dark line. Thus, the luminance can beimproved by the decrease in the number of the dark lines X1.

As described above, according to this embodiment, the displaycharacteristics of the liquid crystal display can be greatly improved inwhich monomers that are polymerized by heat or light are polymerized andthe pretilt angle of the liquid crystal molecule and/or the tiltdirection at the time of voltage application is regulated.

The present invention is not limited to the above-described embodiments,and various modifications may be made. For example, the aboveembodiments relates to the LCD having n-channel TFTs, however, theinvention is obviously applicable to the LCD having p-channel TFTs.

Therefore, the above object can be achieved by a method of manufacturinga liquid crystal display having p-channel TFTs, comprising the steps ofsealing a liquid crystal layer containing a polymerizable component,which is polymerized by light or heat, between substrates, andpolymerizing the polymerizable component while a voltage is applied tothe liquid crystal layer, to regulate a pretilt angle of a liquidcrystal molecule and/or a tilt direction at a time of driving, whereinthe voltage is applied to the liquid crystal layer under a voltageapplication condition 2 subsequently to a voltage application condition1 mentioned below, and the polymerizable component is polymerized at astage of the voltage application condition 2;

the voltage application condition 1: Vg<Vd(dc)=Vc,

and the voltage application condition 2: Vc<Vd(dc)

where,

Vg: applied voltage to a gate bus line,

Vc: applied voltage to a common electrode, and

Vd (dc): applied voltage (direct-current component) to a drain bus line.

Also, the above object can be achieved by a method of manufacturing aliquid crystal display having p-channel TFTs, comprising the steps ofsealing a liquid crystal layer containing a polymerizable component,which is polymerized by light or heat, between substrates, andpolymerizing the polymerizable component while a voltage is applied tothe liquid crystal layer, to regulate a pretilt angle of a liquidcrystal molecule and/or a tilt direction at a time of driving, whereinthe voltage is applied to the liquid crystal layer under a voltageapplication condition 2 subsequently to a voltage application condition1 mentioned below, and further, the voltage is applied to the liquidcrystal layer under a voltage application condition 3, and thepolymerizable component is polymerized at a stage of the voltageapplication condition 3;

the voltage application condition 1: Vg<Vd(dc)=Vc, Vd(ac)=0,

the voltage application condition 2: Vc<Vd(dc), and

the voltage application condition 3: while Vc is made to approach Vd(dc), Vd (ac) is gradually made higher than 0,

where,

Vg: applied voltage to a gate bus line,

Vc: applied voltage to a common electrode,

Vd (dc): applied voltage (direct-current component) to a drain bus line,and

Vd (ac): applied voltage (alternating component) to the drain bus line.

Also, the above object can be achieved by a method of manufacturing aliquid crystal display having p-channel TFTs, comprising the steps ofsealing a liquid crystal layer containing a polymerizable component,which is polymerized by light or heat, between substrates, andpolymerizing the polymerizable component while a voltage is applied tothe liquid crystal layer, to regulate a pretilt angle of a liquidcrystal molecule and/or a tilt direction at a time of driving, whereinthe voltage is applied to the liquid crystal layer under a voltageapplication condition 2 subsequently to a voltage application condition1 mentioned below, and further, the voltage is applied to the liquidcrystal layer under a voltage application condition 3, and thepolymerizable component is polymerized at a stage of the voltageapplication condition 3;

the voltage application condition 1: Vg<Vd (dc)=Vc,

the voltage application condition 2: Vc<Vd (dc), and

the voltage application condition 3: Vg is increased and is made toapproach Vd (dc),

where,

Vg: applied voltage to a gate bus line,

Vc: applied voltage to a common electrode, and

Vd (dc): applied voltage (direct-current component) to a drain bus line.

Also, the above object can be achieved by a method of manufacturing aliquid crystal display having p-channel TFTs, comprising the steps ofsealing a liquid crystal layer containing a polymerizable component,which is polymerized by light or heat, between substrates, andpolymerizing the polymerizable component while a voltage is applied tothe liquid crystal layer, to regulate a pretilt angle of a liquidcrystal molecule and/or a tilt direction at a time of driving, whereinthe voltage is applied to the liquid crystal layer under a voltageapplication condition 2 subsequently to a voltage application condition1 mentioned below, and next, the voltage is applied to the liquidcrystal layer under a voltage application condition 3, and further, thevoltage is applied to the liquid crystal layer under a voltageapplication condition 4, and the polymerizable component is polymerizedat a stage of the voltage application condition 4;

the voltage application condition 1: Vg<Vd(dc)=Vc, Vd (ac)=0,

the voltage application condition 2: Vc<Vd (dc),

the voltage application condition 3: while Vc is made to approach Vd(dc), Vd (ac) is gradually made higher than 0, and

the voltage application condition 4: Vg is increased and is made toapproach Vd (dc),

where,

Vg: applied voltage to a gate bus line,

Vc: applied voltage to a common electrode,

Vd (dc): applied voltage (direct-current component) to a drain bus line,and

Vd (ac): applied voltage (alternating component) to the drain bus line.

In the method of manufacturing a liquid crystal display having p-channelTFTs described above, when the applied voltage Vg to the gate bus lineis decreased and is made to approach the applied voltage (direct currentcomponent) Vd (dc) to the drain bus line, the applied voltage Vg is madeequal to the applied voltage Vd (dc).

In the method of manufacturing a liquid crystal display having p-channelTFTs described above, at a time of voltage application of Vc<Vd (dc), avalue of Vc−Vd (dc) is once made lower than a desired voltage, and then,the voltage is uppered to the desired voltage.

In the method of manufacturing a liquid crystal display having p-channelTFTs described above, the applied voltage Vg to the gate bus line is adirect-current voltage.

Second Embodiment

Next, a liquid crystal display according to a second embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIGS. 22A to 45. The TN mode which wasconventionally the main current of an active matrix type LCD has adefect that an angle of view is narrow. Then, at present, techniquescalled an MVA mode and an IPS mode (In-Plane-Switching mode) are adoptedfor an LCD of a wide angle of view.

In the IPS mode, a liquid crystal molecule is switched by a combelectrode in a horizontal plane, however, since the comb electroderemarkably lowers the opening ratio of a pixel, a backlight of highoptical intensity becomes necessary. In the MVA mode, liquid crystal isaligned vertically to the substrate, and the alignment of a liquidcrystal molecule is regulated by a protrusion or a slit provided in atransparent electrode (ITO).

Although a drop in the substantial opening ratio of a pixel by theprotrusion or the slit in the MVA mode is not more than that by the combelectrode, as compared with the TN mode, the light transmissivity of aliquid crystal panel is low. Thus, in the present circumstances, theMVA-LCD is not adopted for a book-size personal computer which requiresa low power consumption.

In the present MVA-LCD, for realizing a wide angle of view, the linearprotrusions or the slits obtained by linearly cutting away part of apixel electrode are complicatedly arranged in a pixel so that the liquidcrystal molecules fall down in four directions at the time of voltageapplication. Thus, the light transmissivity of the pixel becomes low. Adescription will be given of a case where in order to improve this, asshown in FIGS. 22A and 22B, straight linear protrusions are simplyarranged at wide intervals in parallel with each other.

FIGS. 22A and 22B show an MVA-LCD including half divided alignmentregions. FIG. 22A shows a state in which one pixel 2 of the MVA-LCD isviewed in the direction of a normal of a substrate surface. FIG. 22Bshows a section taken along a line parallel with a drain bus line 6 ofthe MVA-LCD shown in FIG. 22A. Incidentally, in the subsequentdescription of the embodiment, a structural element having the sameoperation and function as a structural element explained before isdesignated by the same symbol and its explanation is omitted. FIG. 22Ashows three pixels 2 continuously connected to one gate bus line 4. Asshown in FIGS. 22A and 22B, two linear protrusions 68 extending inparallel with the gate bus line 4 are formed in the vicinity of both endportions of a pixel electrode 3 on the side of the gate bus line 4.Besides, on a common electrode on the side of an opposite substrate, alinear protrusion 66 extending in parallel with the gate bus line 4 isformed at a position including the center of the pixel. Incidentally, onthe side of the array substrate, an insulating film (gate insulatingfilm) 23 is formed on a glass substrate 20 and the gate bus line 4, andan insulating film 22 is formed thereon.

By this construction, when a voltage is applied between a pixelelectrode 3 and a common electrode 26 and an electric field distributionin a liquid crystal layer 24 is changed, liquid crystal molecules 24 ahaving a negative dielectric anisotropy are tilted in two directions.That is, the liquid crystal molecules 24 a are tilted toward the linearprotrusion 66 on the side of the opposite substrate from the linearprotrusions 68 of both ends of the pixel 2 on the side of the gate busline 4. By this, an upper and lower half divided multiple domain isformed. In the MVA mode, the tilt direction is regulated in order fromthe liquid crystal molecules 24 a in the vicinity of the linearprotrusions 66 and 68 (or in the vicinity of the slit) by the electricfield generated by the linear protrusions (or slits). Accordingly, asshown in FIGS. 22A and 22B, if the interval between the linearprotrusions (or slits) is very wide, it takes a time to propagate thetilt of the liquid crystal molecule 24 a, so that the response of thepanel when voltage is applied becomes very slow.

Then, the polymer fixation system has been adopted which uses the liquidcrystal layer 24 containing a polymerizable monomer instead of aconventional liquid crystal material. In the polymer fixation system,monomers are polymerized into polymers in the state where a voltage isapplied to the liquid crystal layer 24, so that the direction of thetilt of the liquid crystal molecule 24 a is memorized in the polymer.

However, even if the voltage is applied to the liquid crystal layer 24in the construction of FIGS. 22A and 22B, the liquid crystal molecule 24a in the vicinity of the drain bus line 6 falls down in the directiondifferent from an intended tilt direction by 90° by the electric fieldgenerated at the end portion of the pixel electrode 3 in the vicinity ofthe drain bus line 6. Thus, even if the polymer fixation system is used,as in a microscopic observation view of FIG. 23, a large dark portion X1is seen along the drain bus line 6 in each of the display pixels 2.

Then, in this embodiment, a pixel electrode 3 on the side of an arraysubstrate in which a TFT 16 is provided is made a stripe-like electrodeof a line and space pattern. As an example, FIG. 24 shows an example inwhich the one pixel 2 of the MVA-LCD according to this embodiment isviewed in the direction of the normal of the substrate surface. As shownin FIG. 24, the pixel electrode 3 includes the stripe-like electrodes 8and the spaces 10 in which the line and space pattern is formed inparallel with the drain bus line 6.

In general, an alignment regulating force by an alignment film isexerted on only the liquid crystal molecule 24 a in contact with thealignment film, and is not exerted on the liquid crystal molecule at thecenter portion in the cell gap direction. Thus, the liquid crystalmolecule 24 a of the center portion in the cell gap direction greatlyreceives the influence of the electric field generated at the endportion of the pixel and the alignment orientation is disturbed. Whenthe pixel electrode 3 including the stripe-like electrodes 8 and thespaces 10 parallel with the drain bus line 6 is adopted, the liquidcrystal molecules 24 a fall down in parallel with the stripe-likeelectrodes 8 and the spaces 10. Besides, since the tilt directions ofall the liquid crystal molecules 24 a are determined by the stripe-likeelectrodes 8 and the spaces 10, the influence of the electric fieldgenerated at the end portion of the pixel can be suppressed to aminimum.

A liquid crystal display according to this embodiment and a method ofmanufacturing the same will be specifically described below usingexamples. First, conditions common to all examples are listed below;

orientation film: vertical orientation film;liquid crystal: having a negative dielectric anisotropy;polarizing plate: arranged at both sides of a liquid crystal panel incrossed Nicols and realizing a normally-black mode;polarization axis of polarizing plate: direction of 45° with respect toa bus line;liquid crystal panel: 15 inches in diagonal; andresolution: XGA.

Example 2-1

This example will be described with reference to FIGS. 24 to 27. FIG. 24shows a state in which one pixel 2 of an MVA-LCD according to thisexample is viewed in the direction of a normal of a substrate surface,and FIG. 25 shows a sectional shape taken along line D-D of FIG. 24. Asshown in FIG. 24, a pixel electrode 3 includes stripe-like electrodes 8and spaces 10 in which a line and space pattern is formed in parallelwith a drain bus line 6. The respective stripe-like electrodes 8 areelectrically connected to each other by a connection electrode 64 formedat the substantially center portion of the pixel 2 and in parallel witha gate bus line 4. Besides, part of the stripe-like electrodes 8 areconnected to a source electrode 62 arranged opposite to a drainelectrode 60 of a TFT 16.

As shown in FIG. 25, a linear protrusion 66 extending in parallel withthe gate bus line 4 is formed on the side of an opposite substrate at aposition opposite to the connection electrode 64 of the center portionof the pixel region. The alignment regulating direction of the liquidcrystal molecule 24 a can be more remarkably determined by the linearprotrusion 66.

Instead of providing the linear protrusion 66 on the side of theopposite substrate, a rubbing processing may be naturally performed tothe alignment film on the side of the array substrate or on the side ofthe opposite substrate. In this case, as indicated by arrows shown inFIG. 25, the rubbing processing on the side of the array substrate isperformed toward the connection electrode 64 in both regions B and Cshown in FIG. 24. The rubbing processing on the side of the oppositesubstrate is performed in the direction of going away from theconnection electrode 64. Besides, it is also possible to use opticalalignment.

Incidentally, there is a case where an alignment disturbance occurs suchthat the tilt direction of a liquid crystal molecule 24 b in a region Asurrounded by a broken line in the vicinity of a TFT 16 shown in FIG. 24becomes reverse to that of the liquid crystal molecule 24 a of a regionB as shown in FIG. 25. By this alignment disturbance, a dark portion isformed in the region A at the time of voltage application to the liquidcrystal layer 24. FIG. 26 shows a modified example for improving this.In this modified example, as shown in FIG. 26, two linear protrusions 68extending in parallel with a gate bus line 4 are formed in the vicinityof both end portions of a pixel electrode 3 on the side of the gate busline 4. When the linear protrusion 68 is provided over the gate bus lineand between the gate bus line 4 and the pixel electrode 3, the directionin which the liquid crystal molecule 24 b of the region A falls down canbe made the same direction as the liquid crystal molecule 24 a of theregion B.

The construction of the modified example of FIG. 26 was used, and in thestate where the liquid crystal molecule 24 a in the pixel 2 was tiltedin a predetermined direction by applying a voltage to the liquid crystallayer 24, light was irradiated to the liquid crystal added with aphoto-polymerizable monomer to polymerize the monomer, and the fixationof the pretilt angle and/or the alignment orientation of the liquidcrystal molecule 24 a was realized. When a display was effected on thecompleted MVA-LCD and the display region was observed, light wastransmitted through the whole pixel portion, and in a T-V characteristicdiagram of FIG. 27, as indicated by a curved line of a solid line, thetransmissivity could be improved as compared with a conventional LCDindicated by a broken line.

Example 2-2

This example will be described with reference to FIGS. 28 to 31. FIG. 28shows a state in which one pixel 2 of an MVA-LCD according to thisexample is viewed in the direction of a normal of a substrate surface,and FIG. 29 shows a sectional shape taken along line E-E of FIG. 28. Asshown in FIG. 28, a pixel electrode 3 includes stripe-like electrodes 8and spaces 10 in which a line and space pattern is formed in parallelwith a drain bus line 6. The respective stripe-like electrodes 8 areelectrically connected to each other by two connection electrodes 64formed in parallel with a gate bus line 4 at upper and lower ends of apixel 2. Besides, the connection electrode 64 at the upper portion inthe drawing is connected to a source electrode 62 of a TFT 16.

As shown in FIG. 29, a linear protrusion 68 extending in parallel withthe gate bus line 4 is formed on the pixel electrode 3 at the centerportion of a pixel region. The alignment orientations in regions A and Bare made the same by the linear protrusion 68, whereas the alignmentorientation of a region C can be made opposite to that of the regions Aand B. The liquid crystal alignment orientations in the regions B and Cof this example become reverse to the liquid crystal alignmentorientations of the regions B and C in the example 2-1.

Instead of providing the linear protrusion 68 on the pixel electrode 3,a rubbing processing may be naturally performed to an alignment film onthe side of an array substrate or on the side of an opposite substrate.In this case, as indicated by arrows shown in FIG. 29, on the side ofthe array substrate, rubbing is performed toward the outside connectionelectrodes 64 in both the regions B and C shown in FIG. 28. On the sideof the opposite substrate, rubbing is performed from the connectionelectrodes 64 to the center portion of the pixel. Besides, opticalalignment can also be used.

Incidentally, there is a case where an alignment disturbance as shown inFIG. 29 occurs in a liquid crystal molecule 24 b of regions D surroundedby broken lines in the vicinity of the two connection electrodes 64shown in FIG. 28. By this alignment disturbance, a dark portion isformed in the region D at the time of voltage application to a liquidcrystal layer 24. FIG. 30 shows a modified example for improving this.In this modified example, as shown in FIG. 30, two linear protrusions 66extending in parallel with a gate bus line 4 are formed on the side ofan opposite substrate at positions opposite to connection electrodes 64in the vicinity of both end portions of a pixel electrode 3 on the sideof the gate bus line 4. When the linear protrusion 66 is disposedbetween the gate bus line 4 and the pixel electrode 3 when viewed in thedirection of a normal of a substrate surface, the direction in which theliquid crystal molecule 24 b of the region D falls down can be made thesame direction as the liquid crystal molecule 24 a of the region B orthe region C.

The construction of the modified example of FIG. 30 was used, and in thestate where the liquid crystal molecule 24 a in the pixel 2 was tiltedin a predetermined direction by applying a voltage to the liquid crystallayer 24, light was irradiated to the liquid crystal added with aphoto-polymerizable monomer to polymerize the monomer, and the fixationof the pretilt angle and/or the alignment orientation of the liquidcrystal molecule 24 a was realized. When a display was effected on thecompleted MVA-LCD and the display region was observed, light wastransmitted through the whole pixel portion, and in a T-V characteristicdiagram of FIG. 31, as indicated by a curved line of a thick solid line,the transmissivity could be improved as compared with a conventional LCDindicated by a thin solid line.

Example 2-3

This example will be described with reference to FIGS. 32 to 34. FIG. 32shows a state in which two adjacent pixels 2 of an MVA-LCD according tothis example are viewed in the direction of a normal of a substratesurface. The structure of a pixel electrode 3 according to this exampleis the same as the example 2-1. This example is characterized in that anelectric field shielding electrode 70 is provided which decreases ahorizontal electric field generated between a stripe-like electrode 8 onthe side of a drain bus line 6 of the pixel electrode 3 and the drainbus line 6. As shown in a sectional view of FIG. 33, the electric fieldshielding electrode 70 is formed below a region between the stripe-likeelectrode 8 at the end portion of the drain bus line 6 of the pixelelectrode 3 and the drain bus line 6 and by using gate formation metalat the same time as the gate bus line 4.

FIG. 33 is a view showing the arrangement position of the electric fieldshielding electrode 70 and the operation. A voltage is applied to thepixel electrode 3 and the electric field shielding electrode 70, and asshown in FIG. 33, equipotential lines almost parallel with the substratesurface are generated in the array substrate. By doing so, as shown inan ellipse 72 of a broken line in FIG. 33, it is possible to prevent thegeneration of the horizontal electric field in the region between thestripe-like electrode 8 at the end portion of the drain bus line 6 andthe drain bus line 6. The equipotential lines and liquid crystaldirectors are shown in FIG. 33, and it is understood that theequipotential lines are almost parallel with the substrate surface inthe ellipse 72, and the directors are almost perpendicular to thesubstrate surface.

Monomers in the liquid crystal layer 24 are polymerized in this state.After the monomers are polymerized, the electric field shieldingelectrode 70 is electrically connected to a common electrode 26 and isused as a storage capacitance electrode. Since the direction in whichthe liquid crystal molecules 24 a falls down is determined by thepolymerized polymer, it hardly receives the influence of the electricfield generated at the end of the pixel. When a display was effected onthe completed MVA-LCD and the display region was observed, light wastransmitted through the whole pixel portion, and in a T-V characteristicdiagram of FIG. 34, as indicated by a curved line of a thick solid line,the transmissivity could be improved as compared with a conventional LCDindicated by a thin solid line.

Example 2-4

This example will be described with reference to FIGS. 35 and 36. FIG.35 shows a state in which one pixel 2 of an MVA-LCD according to thisexample is viewed in the direction of a normal of a substrate surface.The construction of a pixel electrode 3 according to this example is thesame as the example 2-1.

This example is characterized in that an alignment orientation on analignment film on a region 74 indicated by a broken line at an endportion of the pixel electrode 3 in the vicinity of a drain bus line 6is made to have a direction different from that at the center portion ofthe pixel. As shown in FIG. 35, liquid crystal molecules 24 a are tilteddownward on the paper plane (downward thick arrow) in a pixel regionabove the center portion of the pixel in the drawing, and are tiltedupward on the paper plane (upward thick arrow) in a lower pixel region.On the other hand, in the region 74, an alignment processing isperformed so that an alignment orientation (thin arrow) is inclined atapproximately 45° with respect to the extension direction of theadjacent drain bus line 6. In this example, ultraviolet light wasirradiated to perform an alignment processing.

When a voltage is applied to a pixel, the alignment direction of aliquid crystal molecule is determined by balance of both of thealignment processing and the electric field. By this, since the liquidcrystal molecule 24 a of the end region 74 of the pixel electrode 3 alsofalls down in the direction almost parallel to the drain bus line 6,light can be transmitted through the whole pixel electrode.

In this state, monomers in the liquid crystal layer 24 are polymerized.Since the direction in which the liquid crystal molecule 24 a falls downis determined by a polymerized polymer, it hardly receives the influenceof an electric field generated at the end of the pixel. When a displaywas effected on the completed MVA-LCD and the display region wasobserved, light was transmitted through the whole pixel portion, and ina T-V characteristic diagram of FIG. 36, as indicated by a curved lineof a thick solid line, the transmissivity could be improved as comparedwith a conventional LCD indicated by a thin solid line.

Example 2-5

This example will be described with reference to FIGS. 37 to 40. FIG. 37shows a state in which one pixel 2 of an MVA-LCD according to thisexample is viewed in the direction of a normal of a substrate surface.Although the structure of a pixel electrode 3 of this example is thesame as the example 2-1, this example is characterized in that the widthof a gap 76 between a drain bus line 6 and a pixel electrode 3 is madeequal to the width of a space 10 in the pixel electrode 3.

FIG. 38 shows a construction in which the gap 76 between the drain busline 6 and the pixel electrode 3 is wide. When the width of the region76 along the substrate surface is made “a”, and the width of the space10 is made “b”, a>b is satisfied. Since capacitance between the drainbus line 6 and the pixel electrode 3 becomes the cause of crosstalk, thegap 76 is generally made wide. However, when a voltage is applied to theliquid crystal layer 24, a liquid crystal molecule 24 a in a region 76 aindicated by an ellipse over the gap 76 falls down in the directionperpendicular to the drain bus line 6, and a dark portion appears in thepixel. On the other hand, in a region 10 a over the space 10 in thepixel electrode 3, a liquid crystal molecule 24 a is tilted in parallelwith the extension direction of the space.

Then, as shown in FIG. 39, the gap 76 is made close to the width of thespace 10 to satisfy a≅b, and the liquid crystal molecule 24 a in theregion 76 a is also made to fall down in the direction parallel with thedrain bus line 6. By doing so, since the area of the pixel electrode 3can also be widened, there is an effect that the transmissivity can beimproved double as shown in FIG. 39. In order to suppress the crosstalk, as shown in FIG. 39, an electric field shielding electrode 70 ofthe example 2-3 has only to be provided in a lower layer of the gap 76.

In this construction, a voltage is applied to the liquid crystal layer24 and monomers in the liquid crystal layer 24 are polymerized. Sincethe direction in which the liquid crystal molecule 24 a falls down isdetermined by the polymerized polymer in the completed MVA-LCD, ithardly receives the influence of an electric field generated at the endof the pixel when an image is displayed. When a display was effected onthe completed MVA-LCD and the display region was observed, light wastransmitted through the whole pixel portion, and in a T-V characteristicdiagram of FIG. 40, as indicated by a curved line of a solid line, thetransmissivity could be improved as compared with a conventional LCDindicated by a broken line.

Example 2-6

This example will be described with reference to FIGS. 41 to 45. FIG. 41shows a state in which one pixel 2 of an MVA-LCD according to thisexample is viewed in the direction of a normal of a substrate surface.The structure of a pixel electrode 3 of this example is characterized inthat a line and space pattern constituted by stripe-like electrodes 8and spaces 10 is formed in parallel with a gate bus line 4. In order toproduce alignment division in two directions of right and leftdirections in the drawing, a connection electrode 64 is provided at theright side in the upper half of the pixel, and a connection electrode 64is provided at the left side in the lower half of the pixel. By doingso, the alignment of a liquid crystal molecule tilted in a directionperpendicular to a drain bus line 6 by a horizontal electric fieldgenerated at the end of the pixel electrode parallel with the drain busline 6 can be actively used. Incidentally, the connection electrodes 64may be naturally provided at the left side in the upper half of thepixel and at the right side in the lower half of the pixel.

FIG. 42 shows a section taken along line F-F of FIG. 41. FIG. 43 shows asection taken along line G-G of FIG. 41. As shown in FIGS. 42 and 43, alinear protrusion 66 is formed on an opposite substrate between thedrain bus lines 6 adjacent to the two connection electrodes 64. Byforming the linear protrusion 66, the influence of an electric fieldbetween the connection electrode 64 and the adjacent drain bus line 6can be eliminated. Further, in order to ensure the alignment direction,as indicated by a thick outlined arrow of FIG. 44, on the side of thearray substrate, rubbing may be performed from the side where theconnection electrode 64 is not provided toward the side of theconnection electrode 64, and on the side of the opposite substrate,rubbing may be performed in the direction opposite to the arrow.Besides, an optical alignment processing may be performed.

In this construction, a voltage is applied to the liquid crystal layer24 to polymerize monomers in the liquid crystal layer 24. In thecompleted MVA-LCD, since the direction in which the liquid crystalmolecule 24 a falls down is determined by the polymerized polymer, ithardly receives the influence of the electric field generated at the endof the pixel when an image is displayed. When a display was effected onthe completed MVA-LCD and the display region was observed, light wastransmitted through the whole pixel portion, and in a T-V characteristicdiagram of FIG. 45, as indicated by a curved line of a thick solid line,the transmissivity could be improved as compared with a conventional LCDindicated by a thin solid line.

Third Embodiment

Next, a liquid crystal display according to a third embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIGS. 46A to 48. This embodiment relates toan improvement of the MVA-LCD of the second embodiment. According to thesecond embodiment, a large dark portion X1 as indicated in the pixelmicroscopic observation view of FIG. 23 can be reduced using thestripe-like electrode pattern, however, a dark portion X1 slightlyremains over the stripe-like electrode 8 closest to the drain bus line 6and the gap 76.

FIGS. 46A to 46E are views for explaining a tilting operation of aliquid crystal molecule 24 a. FIG. 46A shows a state in which a pixelelectrode 3 having no slit and the liquid crystal molecule 24 a areviewed in the direction of a normal of a substrate surface, and FIG. 46Bshows a state in which they are viewed in the direction of a section ofthe substrate. As shown in FIGS. 46A and 46B, when a voltage is appliedto the liquid crystal molecule 24 a, the major axis of the liquidcrystal molecule 24 a is tilted in the direction perpendicular to theend side of the pixel electrode 3. For example, the liquid crystalmolecule 24 a in the vicinity of the end side of the pixel electrode 3parallel with the drain bus line 6 falls down in the directionperpendicular to the extension direction of the drain bus line 6.

FIG. 46C shows a state in which a pixel electrode 3 formed of a line andspace pattern and constituted by stripe-like electrodes 8 and spaces 10,and a liquid crystal molecule 24 a are viewed in the direction of anormal of a substrate surface, and FIG. 46D shows a state in which theyare viewed in the direction of a section of the substrate. As shown inFIGS. 46C and 46D, when a voltage is applied to the liquid crystalmolecule 24 a, the major axis of the liquid crystal molecule 24 a istilted in parallel with the longitudinal direction of the pattern of thestripe-like electrodes 8 and the spaces 10.

Accordingly, as shown in FIG. 46E, when the stripe-like electrode 8 isprovided in parallel with a drain bus line 6, the direction of tiltingof the major axis of the liquid crystal molecule 24 a on the stripe-likeelectrode 8 and that in the vicinity of the drain bus line 6 aredifferent from each other by 90°. Thus, a liquid crystal molecule 24 apointing to the direction of 45° with respect to the drain bus line 6 isproduced as shown in an elliptical region 78 of FIG. 46E, and becomesparallel with the polarization axis of a polarizing plate, so that adark portion is observed.

Then, in this embodiment, in order to basically eliminate the influenceof the electric field generated at the end of the pixel and to suppressthe region of the dark portion to a minimum, an electrode width a′ ofthe stripe-like electrode 8 closest to the drain bus line 6 is madethinner than an electrode width b′ of the stripe-like electrode 8 at thecenter portion of the pixel.

Incidentally, if the electrode width a′ of the stripe-like electrode 8is excessively thin, there is a possibility that the stripe-likeelectrode 8 is broken or is short-circuited to the adjacent stripe-likeelectrode 8. Then, the width of the stripe-like electrode 8 and thespace 10 are set to be from 0.5 μm to 5 μm.

The liquid crystal display according to this embodiment and the methodof manufacturing the same will be specifically described below usingexamples. First, conditions of the following examples are the same asthe conditions of the examples in the second embodiment.

Example 3-1

When the distance between the stripe-like electrode 8 and the drain busline 6 is short as in the example 2-5 of the second embodiment, there isa case where capacitance between the pixel electrode 3 and the drain busline 6 becomes large, and cross talk is generated. In this case, sincethe distance between the stripe-like electrode 8 and the drain bus line6 can not be shortened, the region of the dark portion X1 can be made aminimum by narrowing the width of stripe-like electrode 8′ closest tothe drain bus line 6. FIG. 47 exemplifies a case where a connectionelectrode 64 is provided at the center of a pixel. FIG. 48 exemplifies acase where a connection electrode 64 is provided on the side of a gatebus line 4.

Example 3-2

In the example 3-1, in order to prevent the cross talk, the electricfield shielding electrode 70 described in the example 2-3 or the example2-5 of the second embodiment can be used.

Fourth Embodiment

Next, a liquid crystal display according to a fourth embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIGS. 49 to 62. This embodiment relates toan improvement in characteristics of a high display quality MVA-LCD. Asan information equipment becomes popular in recent years, a displaypanel is required to have high performance. Thus, an MVA-LCD excellentin display quality is often used. However, the MVA-LCD has a problemthat a response from the time of no voltage application (at the time ofblack display of a normally-black mode) to the time of low voltageapplication (halftone) is slow.

As shown in FIG. 49, in a conventional MVA-LCD, alignment regulatingstructural members (for example, linear protrusions 66 and 68) forregulating the tilt directions of liquid crystal molecules 24 a arelocally distributed (unevenly distributed). Since the alignmentregulating structural members are locally distributed, in a region wherethere is not a structure for regulating a tilt direction and a tiltangle θp of the liquid crystal molecule 24 a as shown in FIG. 50, ittakes a time to propagate the tilt of a liquid crystal alignment.Further, if a boundary of alignment is formed on the structural memberfor regulating the tilt direction, a dark line is formed around thestructural member, and the transmissivity is lowered. As stated above,in the construction in which means for regulating the tilt direction isarranged dispersedly, there is a problem that the liquid crystalalignment at the time of low voltage application is unstable.

Accordingly, since it takes a time for the liquid crystal of the wholepixel to make a response, there arises a problem that it takes a longtime to change a black display (vertical alignment state) to a halftonedisplay (tilt alignment state). Especially, in the case where thehalftone display has a low gradation, since the propagation of theliquid crystal alignment tilt becomes slow, the response time becomesthree or more times as long as a normal time. However, in the alignmentof the case where polymer fixation has been made, the tilt directions ofall portions in the pixel are previously determined. Accordingly, in anymodes in which the alignment is changed while the tilt direction of theliquid crystal is propagated and the response becomes slow under normalconditions, the polymer fixation realizes a great improvement in theresponse. FIG. 86 shows the relation between the gradation and therising time in an LCD including a polymer unfixed liquid crystal and anLCD including a polymer fixed liquid crystal. It is understood that theresponse speed higher by a factor of two to three times can be obtainedby applying the polymer fixation to the normal MVA-LCD. Besides, asanother problem, since the transmissivity is lowered, the displaybecomes dark. As stated above, in the construction in which tiltalignment is dispersed, there is a problem that the response property isdeteriorated and the luminance is lowered because the liquid crystalalignment at the time of low voltage application is unstable.

This embodiment provides the MVA-LCD in which the response time isshortened without lowering the transmissivity, and the liquid crystalalignment at the time of low voltage application is fixed. Especially,in the polymer fixed alignment as the basic construction of thisembodiment, since the tilt directions of all portions concerning displayare previously determined, in any pixel structures in which the tiltdirection of the liquid crystal must be propagated under normalconditions, remarkable speeding-up can be achieved.

FIG. 51 is a structural view of this embodiment. In the drawing, 3×3=9arrangement regions 80 arranged in a matrix form are exemplified. In therespective arrangement regions 80, structural members havingdirectionality in the direction of a substrate surface or slits obtainedby cutting an electrode (hereinafter referred to as directionalstructural members) are arranged. If a directional structure similar tothe directional structural members is formed, as a single body or anaggregate, in a surface reformed region two-dimensionally in the samedirection, the liquid crystal alignment can be tilted in one direction.By this, since a liquid crystal molecule can be tilted in apredetermined direction at the time of voltage application to a liquidcrystal layer 24 when monomer, which is polymerized by light or heat, ispolymerized, the optimum pretilt angle and/or tilt angle at the time ofdriving can be obtained.

In this embodiment, as shown in FIG. 51, the liquid crystal alignment istilted in one direction by the directional structural members providedin the arrangement regions 80 arranged two-dimensionally on thesubstrate surface or by the surface reformed region in which aconfiguration equivalent to these is formed. That is, since the liquidcrystal alignment is tilted at short intervals in one direction, a timein which the tilt of the liquid crystal alignment is propagated becomesshort, and the response time can be shortened. Further, since a domainis not formed on the directional structural member or the surfacereformed region, the transmissivity is not lowered. Further, since thepolymer aligned in the tilt orientation of the liquid crystal is formed,the liquid crystal is stably tilted at the time of low voltageapplication.

The plurality of arrangement regions 80 shown in FIG. 51 are adjacent toeach other to have a horizontal direction gap width WG and a verticaldirection gap width HG. As a formation material of the structural memberarranged in the arrangement region 80, for example, S1800 positivephotoresist of Shipley Corporation is used. The height of the structuralmember is made about 0.3 μm.

FIG. 52 shows an example of the directional structural member or thesurface reformed region in which a triangular recess being one sizesmaller is formed from a triangular outer shape when viewed in thedirection of a normal of a substrate surface. An energy beam such as anultraviolet ray is selectively irradiated for reforming the surface. Thethickness of the liquid crystal layer is made about 4 μm. A verticalalignment film is used as an alignment film, and a liquid crystal havinga negative dielectric anisotropy is used as a liquid crystal. Byproviding the triangular recess, there is produced an effect that aliquid crystal molecule is hard to tilt in the direction of the recess.As shown in FIG. 52, the pattern size can take various sizes of patternsD1 to D4.

At the time of no voltage application, the liquid crystal molecule isaligned substantially perpendicularly to the substrate surface. At thetime of voltage application, the liquid crystal molecule is tilted inone direction by the directional structural member or the surfacereformed region formed to have the same shape as the former. In the casewhere a liquid crystal cell is sandwiched between polarizing platesarranged in crossed Nicols, a black display is obtained at the time ofno voltage application, and a white display is obtained at the time ofvoltage application.

In the case of a structural member of a flat shape having nodirectionality, it is possible to produce directionality by combination.FIG. 53 shows an example in which a rectangular plane shape having twoaxial symmetry axes and a rectangular plane shape having two axialsymmetry axes are combined to make one axial symmetry axis. As shown inFIG. 53, the pattern size can take various sizes of patterns F1 to F4.

A triangle, an almost halved ellipse, or a semicircle can be used asanother example of the plane shape of the directional structural memberor the surface reformed region. In the case of an equilateral triangle,the number of axial symmetry axes becomes three. However, if it isarranged in a lattice shape, the number of axial symmetry axes of anaggregate becomes one.

FIGS. 54A to 54F show examples of the combination of plural structuralmembers. The plane shape of the directional structural member or thesurface reformed region is substantially triangular, rectangular,square, substantially halved elliptical, semicircular, elliptical orcircular, and one of a protrusion and a recess formed on a side oppositeto the protrusion, or both may be provided in a portion. The shape ofthe protrusion or the recess may be substantially triangular,rectangular, square, halved elliptical, or semicircular.

FIGS. 55 to 58 show constructions for improving a visual angle propertyof an LCD. Directions D of plane shapes of directional structuralmembers or surface reformed regions in a pixel 2 are different. In FIG.55, the inside of the pixel 2 is divided at the center into two regions.For example, the structural members each having the triangular outershape with the recess shown in FIG. 52 are aligned in a matrix form inone direction D1 while the apexes point upward in the drawing. On theother hand, the structural members each having the triangular outershape with the recess shown in FIG. 52 are aligned in a matrix form in areverse direction D2 different from the direction D1 by 180° while theapexes point downward in the drawing. By adopting the construction asstated above, liquid crystal molecules are alignment regulated in a widerange in the pixel at the time of polymerization, and an excellentliquid crystal alignment by polymers can be obtained.

Similarly, in FIG. 56, structural members each having the triangularouter shape with the recess shown in FIG. 52 are aligned in fourdirections D1 to D4 while the directions of the apexes are changed forrespective regions by 90°. Incidentally, the direction of the planeshape may be continuously changed. For example, in FIG. 57, thestructural members are extended radially from the center portion of thepixel 2 and are aligned. In FIG. 58, structural members are aligned suchthat the apexes are concentrically arranged. By adopting the alignmentconstructions as stated above, the directions in which the liquidcrystal molecules are tilted can be finely controlled in the pixel 2, sothat the visual angle property can be improved. Further, a shift of theliquid crystal alignment in the orientation angle direction at the timeof display voltage application can be decreased by previously applying alow voltage to the pixel electrode to slightly tilt the liquid crystalalignment.

What was obtained by adding liquid crystal monoacrylate UCL-001-K1 of2.5% of Dainippon Ink Corporation to liquid crystal MJ-961213 of MerckJapan Corporation was used as a monomer mixture liquid crystal materialfor polymer fixation. After the liquid crystal material is injectedbetween substrates, monomers are cured by irradiating the liquid crystallayer with ultraviolet rays while a voltage of 5.0 V is applied to theliquid crystal layer. By doing so, it becomes possible to form polymersaligned in the tilt orientation of the liquid crystal molecules. Bythis, the liquid crystal alignment at the time of low voltageapplication can be fixed.

Further, a construction for improving the visual angle property of anLCD is shown in FIGS. 59 and 60. The constructions shown in FIGS. 59 and60 are characterized in that a boundary structural member 78 of adirectional structural member or a surface reformed region is providedat a boundary of respective regions in a pixel 2. The boundarystructural member 78 is formed into a band shape having a width of 5 μmand a height of about 0.3 μm. The height may be about 1.5 μm. FIG. 59shows a state in which the inside of the pixel 2 is divided into tworegions by the band-like boundary structural member 78, and FIG. 60shows a state in which the inside of the pixel 2 is divided into fourregions by combining the band-like boundary structural members 78 into acruciform shape.

Constructions shown in FIGS. 61 and 62 are specific examples of theboundary structural member 78 shown in FIG. 60. The structural member 78shown in FIG. 61 is constructed by arranging a plurality of triangularstructures which are radially extended in four directions while thedirections of the apexes are made the same in each direction. Theboundary structural member 78 shown in FIG. 62 is constructed byarranging isosceles triangle structures which are radially extended infour directions while the one structure is extended in one direction andthe apex points to each direction.

As described above, according to this embodiment, the liquid crystalmolecules can be tilted and aligned at short intervals, and thepropagation distance of the liquid crystal alignment tilt becomes short,so that the response time can be made short. Further, since thetransmissivity is not lowered, and the liquid crystal alignment at thetime of low voltage application is stable, the display performance ofthe MVA-LCD can be improved.

Fifth Embodiment

Next, a liquid crystal display according to a fifth embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIGS. 63 to 65. This embodiment relates toweight lightening of the liquid crystal display. The liquid crystaldisplay is used for a portable TV, various monitors, a projection typeprojector, and the like, in addition to a book-size personal computer.

The existing LCD which can produce a color display is inferior to theCRT in brightness, and a rise in luminance is desired. As one of methodsof improving the brightness, it is conceivable to use a circularpolarization plate (circular polarization plate indicates a combinationof a polarizing plate and a λ/4 plate). A drop in luminance bydisclination generated in a pixel can be suppressed by using thecircular polarization plate.

In general, as a method for controlling the alignment of liquid crystal,there is an alignment regulating structural member such as a protrusionor a slit obtained by cutting an electrode. Besides, there is also apolymer fixation system in which monomers are polymerized by irradiatingultraviolet (UV) light to a liquid crystal layer mixed with the monomersin a state where liquid crystal molecules are tilted by applying avoltage to the liquid crystal layer, and the liquid crystal is alignmentregulated. Among these alignment regulating means, the polymer fixationsystem can make the opening ratio of a pixel highest.

When the monomers in the liquid crystal layer are polymerized, a voltageis applied to the liquid crystal layer to tilt the liquid crystalmolecules, and at this time, there is a case where an alignmentregulating structural member is provided in a pixel so that the liquidcrystal molecules keep predetermined alignment directions. In the casewhere the monomers are polymerized without providing the alignmentregulating structural member such as the protrusion or slit, a beadspacer dispersed in the pixel to maintain a predetermined cell gapbecomes a base point for determining the alignment direction of theliquid crystal molecule.

FIG. 63 shows a state in which three adjacent pixels 2 are viewed in thedirection of a normal of a substrate surface. A bead spacer 82 does notexist in a pixel 2 at the left side in the drawing, but one bead spacer82 exists in each of the pixels 2 at the center and the right in thedrawing and the arrangement positions are different from each other.Since the bead spacers 82 are dispersed at random, as shown in FIG. 63,the distribution states of the bead spacers 82 are different for therespective pixels, and accordingly, the base positions for determiningthe alignment directions of liquid crystal molecules 24 a are differentbetween the respective pixels.

When a voltage is applied to a liquid crystal layer 24, the liquidcrystal molecules 24 a in the vicinity of a gate bus line 4 are tiltedin the direction perpendicular to the gate bus line 4 by a horizontalelectric field generated between the gate bus line 4 and the end portionof a pixel electrode 3. Similarly, the liquid crystal molecules 24 a inthe vicinity of a drain bus line 6 are tilted in the directionperpendicular to the drain bus line 6. The tilts of the liquid crystalmolecules 24 a in the vicinity of the bus lines are propagated to theinner liquid crystal molecules 24 a, and four alignment division regionsare formed. Dark lines X1 as shown in the drawing are formed at theboundaries of the respective alignment regions.

However, as described above, since the distribution states of the beadspacers 82 are different between the respective pixels, and the basepositions for determining the alignment directions of the liquid crystalmolecules 24 a are different between the respective pixels, as isapparent from FIG. 63, the formation states of the dark lines X1 becomedifferent between the respective pixels in accordance with the positionsof the bead spacers 82 in the pixels 2. This is caused since thealignment ratios of the respective tilt orientations are differentbetween the respective pixels, and even in the case where the circularpolarization plate is used, there arises a problem that an angle of viewbecomes small at a halftone, brightness becomes different between therespective pixels or unevenness of display is observed on the whole.

In order to improve the above problem, in the liquid crystal displayaccording to this embodiment, columnar spacers are formed at the sameposition in all pixels instead of the bead spacers, so that thealignment ratios of liquid crystal molecules in respective alignmentdirections in the pixel become the same in all pixels. By doing so,since the alignment rates of the liquid crystal molecules in therespective alignment directions become the same in all the pixels,unevenness of display can be prevented.

Hereinafter, a specific example will be described with reference to FIG.64. FIG. 64 shows a state in which three adjacent pixels 2 are viewed inthe direction of a normal of a substrate surface. In FIG. 64, a storagecapacitance bus line 18 is formed under pixel electrodes 3 at theircenter lines, and columnar spacers 84 each having a width of 10 μmsquare are formed of resist on the center of pixel electrodes 3.

As stated above, in the MVA-LCD of this example, instead of the beadspacers, the columnar spacers 84 are formed at the same position (inthis example, at the center of the pixel) of the respective pixels.Thus, the base positions for determining the alignment directions of theliquid crystal molecules 24 a can be the same for all the pixels.Accordingly, as shown in FIG. 64, the alignment ratios of the liquidcrystal molecules 24 a in the respective alignment directions in thepixel 2 are made the same, and the formation states of dark lines X1 inthe pixels 2 can be made the same in all the pixels.

Next, a method of manufacturing the MVA-LCD according to this examplewill be described in brief.

First, a positive resist (made by Shipley Corporation) is spinner coatedto a predetermined thickness (such a thickness that a cell gap becomes 5μm) on an array substrate on which a TFT 16 is formed or an oppositesubstrate on which a color filter is formed. Thereafter, mask exposureis performed, and the columnar spacer 84 having a thickness equivalentto the thickness of a cell gap is formed at the center portion of apixel as shown in FIG. 64.

Next, a vertical alignment film made of polyimide is formed on the arraysubstrate and the opposite substrate.

Next, both the substrates are bonded at a predetermined position, and aliquid crystal having a negative dielectric anisotropy and a monomer,which can be polymerized by UV light, are mixed and in this state, theyare injected between the substrates.

A gate voltage of DC 30 V is applied to the gate bus line 4 of theliquid crystal panel in which the injection is finished, and a drainvoltage of DC 5 V is applied to the drain bus line 6. The oppositeelectrode is the ground voltage. At this time, the horizontal electricfield is generated between the gate bus line 4 or the data bus line 6and the pixel electrode 3, and the liquid crystal molecules 24 a areslowly aligned into the stable state. UV light is irradiated to theliquid crystal layer 24 in this state, and the monomer is cured byphotopolymerization.

Next, circular polarization plates (polarizing plates+λ/4 plates) arearranged on both surfaces of the liquid crystal panel in a predeterminedoptical axis, and the MVA-LCD is completed.

Next, a modified example of the above example will be described withreference to FIG. 65. FIG. 65 shows a state in which three adjacentpixels 2 are viewed in the direction of a normal of a substrate surface.In FIG. 65, two columnar spacers 84 each having a width of 10 μm squareare formed on a horizontal or vertical center line 1 b of a pixelelectrode 3 at equal distances from the center of the pixel 2.Incidentally, the columnar spacer 84 may be naturally cylindrical.Cylindrical spacers 84′ each having a diameter of 10 μm is exemplifiedin the pixel 2 at the left side of FIG. 65. It is desirable that thewidth and the diameter of the columnar spacers 84 and 84′ are 20 μm orless.

As stated above, also in the MVA-LCD of this modified example, insteadof the bead spacers, the two columnar spacers 84 are formed at the samepositions (in this example, upper and lower two positions at equaldistances from the center of the pixel) of each of the pixels. Even ifthis construction is adopted, the base positions for determining thealignment directions of the liquid crystal molecules 24 a can be madethe same in all the pixels.

In the above example and modified example, the columnar spacer 84 isformed using the resist, however, in addition to this, the columnarspacer 84 may be naturally formed by partially stacking two or threelayers of color filter formation material. Besides, it may be formed bystacking plural layers of the color filter formation material and a thinfilm of organic material.

Further, in a CF-on-TFT structure in which a color filter layer isformed on an array substrate, the columnar spacer 84 may be naturallyformed by partially stacking two or three layers of color filter layers.

Besides, in the above example and modified example, although thedescription has been given of the example in which two or three columnarspacers 84 are formed in the pixel, in addition to this, columnarspacers may be naturally formed also on the peripheral portion of thepixel regularly.

Sixth Embodiment

Next, a liquid crystal display according to a sixth embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIGS. 66 to 68B. This embodiment relates toa VA mode in which a liquid crystal having a negative dielectricanisotropy is vertically aligned, and particularly to an MVA-LCD inwhich an alignment control (tilt direction) of liquid crystal moleculesis made without performing an alignment processing such as rubbing butby using an alignment protrusion or an electrode slit. Further, thisembodiment relates to an MVA-LCD which has a wide interval betweenalignment protrusions and is bright, however, has a construction suchthat an alignment control is difficult.

In the MVA-LCD in which the liquid crystal having the negativedielectric anisotropy is vertically aligned, and the tilt directions ofthe liquid crystal molecules at the time of voltage application aredivided into some directions using the alignment protrusions or theelectrode slits, they are vertically aligned almost completely at thetime of no voltage application, however, they are tilted in variousdirections at the time of voltage application. Although the directionsof the tilts are regulated to form 45° with respect to a polarizerabsorption axis in any cases, the liquid crystal molecule as a continuumalso falls down in the intermediate direction. Besides, also by theinfluence of a horizontal electric field or the like at the time ofdriving or the roughness of the structural member, there always exists aregion where the tilt direction of the liquid crystal is shifted from apredetermined direction. In the normally-black mode in which thepolarizers are arranged in crossed Nicols, a blackish region appears ineach pixel at the time of a white display. This lowers the luminance ofthe screen.

Then, the polymer fixation system is effective in which the liquidcrystal molecules fall down to a certain degree by voltage application,and a monomer material is polymerized in the state where the tiltdirection is determined. As the monomer material, a material which ispolymerized by UV irradiation is generally used. In the polymer fixationsystem, a polymer is formed to memorize the information of the tiltingdirection of liquid crystal molecules at the time of voltageapplication. Accordingly, when a state in which there is no disclinationin a liquid crystal layer is formed at the time of polymerization by UVirradiation, the disclination is not produced in the display pixel evenif any liquid crystal driving is performed later. Further, there is amerit that the response speed at a halftone is also improved.

However, it is difficult to apply a uniform voltage to the whole liquidcrystal layer at the time of polymerization. Besides, it is known thatUV irradiation in the on state of a TFT deteriorates the characteristicsof the TFT. Further, it is troublesome in process that UV irradiation ismade while a voltage is applied to the liquid crystal layer. Moreover,if the monomer material in the liquid crystal layer is irregularlydistributed, there is a case where unevenness of in-plane pre-tiltoccurs after the polymerization, and unevenness of display is caused.

In order to solve the above problem, in this embodiment, UV irradiationis applied to monomers to polymerize them in a state of no voltageapplication or in such a low voltage application state that there doesnot occur a difference in pre-tilt even if there is an irregulardistribution of monomer materials. In the state of no voltageapplication, a predetermined effect can be obtained by using aprocessing of optical alignment or the like together.

The UV irradiation is applied under a low voltage of such a degree thata difference does not occur in the pre-tilt even if there is fluctuationof applied voltage to the liquid crystal layer in the substrate surfaceor an irregular distribution of polymer materials in the substratesurface, so that a desired pretilt angle and/or alignment regulatingdirection can be given to the liquid crystal layer, and the occurrenceof the unevenness of display at the time of an image display can beprevented. Further, in combination with a UV alignment, polymerizationcan be performed in the state in which alignment control is perfect evenif a voltage is not applied. Besides, since the TFT can be turned off atthe time of the UV irradiation, deterioration of the TFT can beprevented.

According to this embodiment, the MVA-LCD can be obtained in whichtilting of the liquid crystal molecules is carried out at a high speed,the alignment is fixed, and unevenness of in-plane display does notoccur.

Hereinafter, a specific example will be described with reference toFIGS. 66 to 68B.

FIG. 66 shows a basic construction of an LCD using the polymer fixationsystem. Liquid crystal molecules 24 a are fixed at a pretilt angle bypolymers, and the tilting direction at the time of voltage applicationis also regulated.

FIG. 67A shows a conventional system in which a voltage is applied to aliquid crystal layer 24 when UV irradiation is applied to a monomermaterial to polymerize it. If polymerization is performed by thissystem, the liquid crystal molecules 24 a are fixed at a predeterminedpretilt angle. This pretilt angle is determined by the concentration ofthe polymer material, the voltage applied to the liquid crystal layer24, and the amount of the UV irradiation.

FIG. 67B shows a method of polymerization according to this example. Alight (UV) alignment processing is performed to alignment films (notshown) formed on liquid crystal contact surfaces of a pixel electrode 3and a common electrode 26. By doing so, since it becomes unnecessary toapply a voltage to the liquid crystal layer 24 at the time of UVirradiation, the obtained pretilt angle is determined only by the UValignment processing, and polymerization is performed in this state.Instead of the UV alignment processing, a low voltage of such a degreethat fluctuation does not occur in the pretilt angle may be applied tothe liquid crystal layer to perform polymerization.

FIG. 68A shows results obtained by the conventional system. The leftside and the right side of the drawing show unevenness of pretilt in thecase where there is unevenness of concentration in the polymer materialor there is unevenness of applied voltage to the liquid crystal layer24. In the illustrated example, a left pretilt angle is larger than aright one. As a result, when the completed LCD is displayed, theunevenness of display is observed.

FIG. 68B shows results of this example. In the case where the pretiltangle is determined by the UV alignment processing of the alignmentfilm, or in the case where the low voltage of such a degree thatfluctuation of the pretilt angle does not occur is applied to the liquidcrystal layer, even if unevenness of concentration of the polymermaterial exists on the substrate, since the unevenness of pretilt doesnot occur, the unevenness of display does not occur in the completedLCD.

The monomer material used for this embodiment is a mesomorphism ornon-mesogenic monomer, and for example, bifunctional acrylate or amixture of bifunctional acrylate and monofunctional acrylate can beused.

In this embodiment, although the MVA-LCD has been described, in additionto this, the above embodiment can be applied to LCDs of various systems,such as another VA mode, TN mode, or IPS mode.

Seventh Embodiment

Next, a liquid crystal display according to a seventh embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIG. 69. This embodiment relates to theliquid crystal display and the method of manufacturing the same, andparticularly to the liquid crystal display in which alignment regulationof a vertical alignment type liquid crystal is stably performed by apolymer fixation (macromolecule fixation) system. In a conventionalpolymer fixation system, there is adopted a method in which at the timeof polymerization, the alignment directions of liquid crystal moleculesare controlled by performing light irradiation while a voltage isapplied to the liquid crystal layer from an external power source.

However, this is not an easy process in fabricating the liquid crystaldisplay panel. This is because UV light for polymerization must beirradiated in the state where the voltage is supplied to the liquidcrystal layer from the side of the gate bus line of the liquid crystaldisplay panel, the side of the drain bus line, and the common electrode.

FIG. 69 shows a state in which an array substrate 88 including TFTs andformed on a mother glass 86 on the side of the array substrate, and anopposite substrate 89 bonded thereto across a liquid crystal layer 24are viewed in the direction of a normal of a substrate surface. Polymersfor regulating pretilt angles of liquid crystal molecules and/or tiltdirections at the time of driving are mixed in the liquid crystal layer24. Pixel electrodes are formed in a matrix form on the array substrate88, and a common electrode is formed on the opposite substrate 89. TheTFTs on the array substrate 88 are connected to a gate bus line and adrain bus line.

Solar cells (silicon photovoltaic cells) 74 and 75 are formed on themother glass 86. Output terminals of the solar cell 74 are respectivelyconnected to a plurality of gate bus line terminals led out to the endface of the array substrate 88. Output terminals of the solar cell 75are respectively connected to a plurality of drain bus line terminalsled out to the end face of the array substrate 88.

In a process of fabricating the liquid crystal display panel, thealignment direction of the liquid crystal layer 24 can be regulated byapplying a voltage between the pixel electrode and the common electrodeusing the output voltage obtained by irradiating the solar cells 74 and75 with light. That is, voltage supply from an external power source isnot necessary, and it becomes possible to control the alignmentorientations of the liquid crystal molecules in the process of lightirradiation.

When the alignment orientations of the liquid crystal molecules havebeen fixed, the solar cells 74 and 75 provided on the outer peripheralportion of the mother glass 86 become unnecessary, and accordingly, thesolar cells 74 and 75 are cut away from the panel at scribe lines S1 andS2 when the liquid crystal display panel is cut out from the motherglass 86.

It is desirable in process that the solar cells 74 and 75 are formed onthe mother glass 86 on which the pixel TFTs and active elements includedin a peripheral circuit are formed, and are simultaneously formed whenthe elements of the pixel portion and the peripheral circuit of thearray substrate 88 are formed. When they are formed on the samesubstrate, manufacturing costs can be suppressed.

Besides, the solar cells 74 and 75 are formed on the peripheral portionof the display region, and after the alignment orientation of the liquidcrystal is regulated by irradiation of light, they may be shaded by alight shielding material and may remain in the inside of the liquidcrystal display panel. At this time, in the case where it is used as aliquid crystal display, light shielding must be carried out so that thesolar cells are not operated by a backlight or peripheral light. It isdesirable that the light shielding is carried out by sealing the solarcell portion with a colored resin or a black resin. Further, it is alsoeffective to design a housing so as to shade them from a backlightportion or surrounding light.

The liquid crystal layer of the liquid crystal display of thisembodiment is characterized in that it is of the vertical alignment typeand is subjected to the macromolecule fixation processing. The alignmentorientation of the liquid crystal is determined even at the time of novoltage application by the macromolecular fixation processing, and theliquid crystal molecules have pretilt angles with respect to thesubstrate surface. Such a liquid crystal display panel has a very highcontrast ratio and a high speed response characteristic, and can providea display of high performance. By adopting a multi-domain in which thedirections of liquid crystal alignment molecules by the voltageapplication are two or more directions, a wide visual angle property canalso be obtained.

The plural solar cells 74 and 75 are formed in the mother glass 86, andthey can respectively output independent voltages. That is, varioussolar cells can be formed on the mother glass 86 according to theobjects, for example, the solar cell 74 for gate voltage suppliesvoltage to the gate bus line at polymerization, the solar cell 75 fordrain voltage supplies voltage to the drain bus line, a solar cell isfor a storage capacitance bus line, and so on.

For example, the solar cell 75 may apply voltages suitable forrespective pixel electrodes of R (Red), G (Green) and B (Blue) of theliquid crystal display panel. In the case where the opticalcharacteristics of the liquid crystal display panel are controlled, whenthe liquid crystal alignment is controlled for each of R, G and Bregions, the optical characteristics can be excellent, and at that time,it is advantageous to be capable of controlling the tilt directionbetween the substrate surface and the liquid crystal molecule. It iswell known that a pretilt with a slight inclination of several degrees,such as a pretilt angle of about 87 degrees or 88 degrees, exhibits ahigher speed response property than a tilt angle of 90 degrees as acomplete vertical alignment.

Light is irradiated to perform polymerization, and a construction may beadopted such that the solar cells 74 and 75 are operated by theirradiation light at that time. That is, alignment orienting of theliquid crystal and the polymerization for recording the orienting arecarried out at the same time by simultaneous exposure. When this methodis adopted, a very simple polymerization process can be realized.

It is not always necessary that the light irradiation is performedsimultaneously, and if a process as set forth below can be adopted, itseffect becomes great. The polymerization is performed by a photoreactionof photo-curing macromolecules existing in the liquid crystal layer, andthe wavelength necessary at this time is in a region of ultravioletlight. On the other hand, it is known that the solar cells 74 and 75 areoperated by visible light or the like, and light used for thepolymerization is not always needed. Thus, it is possible to irradiateplural light beams of second and third beams, different from the lightfor polymerization, to the solar cells 74 and 75, the intensities of thelight beams can also be made different from each other, and an outputvoltage corresponding to the light irradiation can be obtained. At thistime, it is also effective to apply a necessary hot wind or heat wind tothe solar cells 74 and 75. By doing so, a voltage suitable for theorienting of the liquid crystal can be applied to the liquid crystaldisplay panel, and it becomes possible to realize a multi-tilt. Ofcourse, it is needless to say that the irradiation light used for thepolymerization includes a visible light component.

The liquid crystal display panel in this embodiment is convenient alsofor the case where it is fabricated by a dropping injection method. Aconstruction can be adopted such that light is irradiated to a main sealcoated on the periphery of the substrate, and the solar cells 74 and 75are operated when a pair of panels are bonded and are fixed.

Besides, a feature is such that from at least one of the liquid crystaldisplay panels, differently from the light for operating the solar cells74 and 75, light is irradiated so that an active element in the pixelshows photoconductivity. Since the active element of the pixel portionproduces the photoconductivity, it becomes possible to reduce or cancelthe applied voltage to the gate side terminal from the solar cells 74and 75, and simplification can be made in the case where the solar cells74 and 75 are formed in the substrate surface. It is preferable thatlight for giving the photoconductivity is irradiated from the side ofthe opposite substrate at the side opposite to the substrate includingthe active element and from an oblique direction of the liquid crystaldisplay panel, and it is appropriate that the light goes round a lightshielding material such as a black matrix (BM).

Eighth Embodiment

Next, a liquid crystal display according to an eighth embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIGS. 70A to 75. This embodiment relates toa method for regulating the alignment of liquid crystal of a VA modeLCD. A conventional TFT liquid crystal display using a TN mode has aproblem that a contrast is lowered when viewed in an oblique direction,or light and darkness of a display is inverted.

In the VA mode liquid crystal display in which liquid crystal moleculesare aligned in the vertical direction with respect to the alignment filmsurface (substrate surface) in the state of no voltage application, acontrast higher than that of the TN mode can be obtained. In the casewhere the VA mode is used, it is generally necessary to give a pretiltangle to the liquid crystal molecule. The pretilt angle is about 1° to5° when measured from a normal of a substrate surface.

In the case where the liquid crystal panel is actually constructed, acell is constructed by bonding two substrates on which the alignmentfilms are formed, and the directions of the pretilt angles given to thealignment films of the two substrates are made opposite to each other.This alignment method is called a homeotropic alignment. When a liquidcrystal having a negative dielectric anisotropy is injected into thecell and a voltage is applied from electrodes provided on the twosubstrates, the liquid crystal molecules are tilted in one direction inwhich the pretilt angle is given. By this, a white display is realizedfrom a black display.

As a method of giving the pretilt angle to the alignment film, methodsas described below are generally adopted. One is a rubbing method inwhich a rotating rubbing cloth is brought into contact with the surfaceof the alignment film to rub it, and the other is an optical alignmentmethod in which ultraviolet rays are irradiated to the surface of thealignment film in an oblique direction.

As a method of widening an angle of view without producing inversion ofan image, there is an alignment division method in which a plurality ofalignment directions of liquid crystal molecules are provided in onepixel. In this method, alignment regulating forces of the pluraldirections must be given onto the alignment film in the minute pixel. Inthis case, since the rubbing method is not suitable for the alignmentdivision, it is suitable to use a method of optical alignment or thelike.

Besides, as a method of strengthening the alignment regulating force ofa tilt vertical alignment, there is a polymer fixation method. This is amethod in which polymerizable monomers are mixed and are polymerized ina liquid crystal layer, and the alignment regulating force isintensified by polymers formed by the polymerization of the monomers,and there are merits that the response time can be made short and highresistance is obtained against an alignment disturbance due to anexternal electric field or the like.

A problem of a case where alignment regulating force is increased by thepolymer fixation method will be described with reference to FIGS. 70Aand 70B. FIGS. 70A and 70B show a state in which two adjacent pixels 2are viewed in the direction of a normal of a substrate surface. FIG. 70Ashows the side of an array substrate in which TFTs 16 are formed. FIG.70B shows a display state of the pixel 2 observed through a black matrix(BM) of a light shielding film provided on the side of an oppositesubstrate. As shown in FIG. 70A, an alignment regulating structuralmember such as a linear protrusion or a slit is not formed on a pixelelectrode 3 in the pixel 2. Thus, when a predetermined voltage isapplied to a gate bus line 4 and a drain bus line 6, liquid crystalmolecules 24 a at the end portion of the pixel electrode 3 as indicatedan arrow 92 in the drawing are tilted toward the inside of the pixelelectrode 3 in the directions perpendicular to the extension directionsof the respective bus lines 4 and 6 by horizontal electric fieldsgenerated between the end portion of the pixel electrode 3 and therespective bus lines 4 and 6.

Even if an initial pretilt angle of a liquid crystal molecule is givenin the direction of an arrow 94 in the drawing by the optical alignmentmethod, since anchoring energy is low in the optical alignment method,the liquid crystal molecule falls down in a direction different from adirection of a given pretilt, for example, a direction different by 90°by the influence of the horizontal electric field between the endportion of the pixel electrode 3 and the drain bus line. Thus, when awhite display is caused, as shown in FIG. 70B, dark portions X1 aregenerated in regions between the pixel electrodes 3 and the drain buslines 6.

In the case where ultraviolet rays are irradiated to polymerizemonomers, the alignment direction memorized in polymers after completiondepends on the alignment direction of the liquid crystal molecules atthe time of polymerization. If ultraviolet rays are irradiated to theliquid crystal layer in this state to perform polymerization and thealignment direction of the liquid crystal molecules is fixed, the darkportions X1 are also memorized and the polymerization is performed.

Then, in this embodiment, when ultraviolet rays are irradiated to theliquid crystal layer to polymerize the monomers, a voltage pattern setforth below is applied to the side of the array substrate on which theTFTs 16 are formed, so that the polymer for regulating an excellentpretilt angle and/or alignment direction is realized without memorizingthe dark portions X1.

(1) A gate voltage Vg (on)=c at which the TFT 16 becomes in an on stateis applied to the gate bus line 4 as a gate pulse of a specifiedfrequency. At a time other than the time of application of the gatepulse, a gate voltage Vg (off) at which the TFT 16 becomes in an offstate is applied.

(2) At the timing when the gate voltage Vg (on) is applied to the gatebus line 4, a drain voltage Vd (on)=a is applied to the drain bus line6, and in the other case, a drain voltage Vd (off)=b is applied. Here,|a|<|b|.

(3) A direct-current voltage of a common voltage Vc=a/2 is applied tothe side of the common electrode. Incidentally, the pulse width of eachof the gate voltage Vg (on), the drain voltage Vd (on) and the drainvoltage Vd (off) is shorter than the pulse width of a writing voltage Vpwritten to the pixel, and for example, it is 1/100 or less of the pulsewidth of the writing voltage Vp.

In the case where a voltage is applied under the above conditions (1) to(3), the writing voltage Vp written to the pixel electrode 3 is thedrain voltage Vd (on) at the time when the TFT 16 is in the on state.Accordingly, the writing voltage is Vp=a, and this voltage is held evenif the TFT 16 is in the off state. The drain voltage Vd (off) applied tothe drain bus line 6 while the writing voltage Vp is held is the pulserepeated at a predetermined frequency and having the maximum amplitudeof b V. A time in which the TFT 16 is in the on state is very short, anda time in which the TFT 16 is in the off state other than that occupiesthe most part, and further, since the drain voltage Vd (off) applied tothe drain bus line 6 is higher than the writing voltage Vp applied tothe pixel electrode 3, the influence of horizontal electric fieldgenerated at the end portion of the pixel electrode 3 can be made small.By this, the width of the dark portion X1 generated at the end portionof the pixel electrode 3 and memorized at the polymerization can be madesmall.

Hereinafter, the liquid crystal display according to this embodiment andthe method of manufacturing the same will be specifically describedusing examples.

Example 8-1

FIG. 71 shows a driving waveform of a liquid crystal display accordingto this example. A pixel pitch (in the longitudinal direction of apixel) in the extension direction of a drain bus line 6 having a widthof 5 μm is 200 μm. On the other hand, a pixel pitch in the extensiondirection of a gate bus line 4 having a width of 5 μm is 70 μm. The endportion of a pixel electrode 3 is located at a position 3 μm away fromthe end portion of the drain bus line 6 or the end portion of the gatebus line 4. The pixel electrode 3 is made of ITO (Indium Tin Oxide) andis connected to a source electrode of a TFT.

A black matrix (BM) having a width of 11 μm is provided on the side ofan opposite substrate at a pitch of 200 μm in a vertical direction and70 μm in a horizontal direction. On the BM, a common electrode made ofITO is provided on almost the whole surface of the substrate. Alignmentfilms are formed on the array substrate and the opposite substrate. Thisalignment film has a vertical alignment property, and a tilt verticalalignment property is given by rubbing the surface of the alignmentfilm.

The array substrate and the opposite substrate are bonded to each otherso that a liquid crystal panel is fabricated. A liquid crystal mixedwith monomers for polymer fixation is injected into this liquid crystalpanel and is sealed.

Under the following procedures, voltage is applied to the liquid crystalpanel in which the liquid crystal has been injected.

(1) A gate voltage Vg (on) of a frequency of 60 Hz is applied to thegate bus line 4 as a pulse so that the TFT 16 becomes in the on state.The gate voltage is Vg (on)=c=18 V. An application time of the gatevoltage Vg (on) is 0.1 ms, and only one pulse is applied in one frame. Aframe frequency is made 16.7 ms, and the gate voltage is made Vg(off)=−5V in 16.7-0.1=16.6 ms. Incidentally, setting is made such thatthe gate voltages Vg (on) and (off) are applied to all the gate buslines 4 at the same time.

(2) A drain voltage Vd (on)=±5 V is applied to the drain bus line 6 atthe timing when the gate voltage Vg (on)=±8 V is applied to the gate busline 4, and at timing other than that, a drain voltage Vd (off)=±8 V isapplied.

A time in which the drain voltage Vd (on) is applied to the drain busline 6 is made equal to or rather longer than the time in which the gatevoltage Vg (on) at which the TFT 16 becomes in the on state is applied.In this example, the drain voltage Vd (on) has a pulse width of at least0.1 ms.

(3) A direct-current voltage corresponding to the center of theamplitude of the drain voltage Vd (on) is applied to the common voltageVc. In this example, the common voltage Vc=0 V.

An applied waveform becomes a waveform as shown in FIG. 71. A writingvoltage Vp=±5 V is applied to the pixel electrode 3 at a frequency of 30Hz and is held until a next writing voltage is applied. On the otherhand, at a time other than the time in which the TFT 16 is in the onstate, the drain voltage Vd (off)=±8 V is applied to the drain bus line6.

By this, it is possible to form such a situation that the voltageapplied to the drain bus line 6 is always higher than the voltageapplied to the pixel electrode 3. In the state where the voltages areapplied to the respective electrodes under the above voltage applicationconditions, ultraviolet rays are irradiated to the liquid crystal layerto polymerize the photo-polymerizable component in the liquid crystal.After the photo-polymerizable component is polymerized, the pretiltangle of the liquid crystal molecule in the liquid crystal layer and/orthe alignment direction is regulated even at the time of no voltageapplication. Thus, the dark portion X1 is not extended even by thedriving voltage at an image display, and the MVA-LCD having highluminance can be realized.

FIGS. 72A and 72B show a state in which two adjacent pixels 2 accordingto this example are viewed in the direction of a normal of a substratesurface. FIG. 72A shows the side of the array substrate on which the TFT16 according to this example is formed. FIG. 72B shows a display stateof the pixel 2 observed through the black matrix (BM) of a lightshielding film provided on the side of the opposite substrate. As shownin FIG. 72A, the predetermined voltages are applied to the gate bus line4 and the drain bus line 6 and even if the horizontal electric fieldsare generated between the end portion of the pixel electrode 3 and therespective bus lines 4 and 6, the liquid crystal molecules 24 a at theend portion of the pixel electrode 3 do not tilt in the directionperpendicular to the extension directions of the respective bus lines 4and 6 by alignment regulation of polymers. Thus, as shown in FIG. 72B,the width of the dark portion X1 generated at the end portion of thepixel electrode 3 along the drain bus line 6 can be reduced.

Example 8-2

This example will be described with reference to FIG. 73. This exampleis characterized in that a drain voltage Vd (off) applied to the drainbus line 6 is made a direct-current voltage instead of an alternatingrectangular voltage as in the example 8-1. As shown in FIG. 73, a pulsevoltage of a drain voltage Vd (on)=+5 V is applied at the timing of agate voltage Vg (on) at which the TFT 16 is in the on state, and attiming other than that, the drain voltage Vd (off)=+8 V is applied.

Ultraviolet rays are irradiated to the liquid crystal layer under theconditions while the voltage is applied, so that the photo-polymerizablecomponent in the liquid crystal is polymerized. Also by this example,since the photo-polymerizable component in the liquid crystal can bepolymerized in the state where the dark portion X1 at the end portion ofthe pixel electrode 3 along the drain bus line 6 is made small, itbecomes possible to fabricate the liquid crystal panel having highluminance in which the dark portion X1 is not generated even at the timeof driving in a normal display mode.

Comparative Example 8-1

FIG. 74 shows a conventional voltage driving waveform as a comparativeexample. As shown in FIG. 74, since the relation of voltages isconventionally drain voltage Vd (on)=drain voltage Vd (off)=writingvoltage Vp, the dark portion X1 is generated by the influence of thehorizontal electric field generated between the drain bus line 6 and theend portion of the pixel electrode 3.

FIG. 75 is a graph in which the drain voltage Vd (off) is taken for thehorizontal axis, and the luminance ratio is taken for the vertical axis.Here, the luminance ratio is made 1 in the case where the drain voltageVd (off) and the writing voltage Vp have the same potential.

As is apparent from FIG. 75, when the drain voltage is Vd (off)=±8 V andthe writing voltage Vp=±5 V of the above example, the luminance ratioexceeding 1.1 is obtained, and the dark portion X1 is sufficientlydecreased.

Besides, it is understood that when the gate voltage Vd (on)=writingvoltage Vp is 5 V or higher, a remarkable effect is obtained. Besides,when the intensity of the voltage of the writing voltage Vp and thedrain voltage Vd (off) is 2 V or higher, a remarkable effect isobtained.

Ninth Embodiment

Next, a liquid crystal display according to a ninth embodiment of thepresent invention and a method of manufacturing the same will bedescribed with reference to FIGS. 76 to 83. This embodiment relates tothe liquid crystal display in which a liquid crystal compositecontaining a photo-polymerizable component is sandwiched betweensubstrates, the photo-polymerizable component is photo-polymerized whilea voltage is applied to the liquid crystal composite, and the liquidcrystal alignment is fixed by this.

In a conventional liquid crystal display device, a TN mode in whichliquid crystals of horizontal alignment are twisted between upper andlower substrates is the main current, however, since the tilt angle ofthe liquid crystal is different according to an observation orientation,that is, an angle of view, gradation inversion occurs at a specificangle of view and at a halftone. Then, a technique called an MVA mode isrealized in which liquid crystal of vertical alignment is tilted insymmetrical orientations to perform compensation of a visual angle. Inthe MVA mode, by forming an alignment regulating structural member madeof dielectric or insulator on an electrode, an oblique electric field isformed in the liquid crystal layer at the time of voltage application,and the liquid crystal is tilted in the predetermined tilt orientationby this oblique electric field.

However, since the voltage applied to the liquid crystal on thealignment regulating structural member is attenuated or becomes zero,the transmissivity per pixel becomes low. In order to ensure thetransmissivity, an occupied ratio of the alignment regulating structuralmember has only to be made low, and for example, a gap between adjacentalignment regulating structural members has only to be made wide.However, if the gap between the alignment regulating structural membersis made wide, there arises a problem that it takes a time to tilt theliquid crystal at the center portion of the gap, and a response timewhen a halftone is display becomes long.

Then, a liquid crystal alignment fixation technique has been proposed inwhich a liquid crystal composite containing a photo-polymerizablecomponent is sandwiched between substrates, the photo-polymerizablecomponent is photo-polymerized to form a cross-linking structurecorresponding to the alignment of liquid crystal while a voltage isapplied, and the liquid crystal alignment is fixed. By this, theresponse time can be shortened while the transmissivity is ensured.

FIG. 76 shows a schematic construction of a liquid crystal display usingthe above alignment fixation technique. FIG. 76 shows a part of an uppersurface of an active matrix type liquid crystal display panel using TFTsas switching elements, viewed from the side of a color filter substrate.As shown in FIG. 76, in a liquid crystal panel 100, a plurality of pixelregions 114 arranged in a matrix form are formed on the side of an arraysubstrate 116, and a TFT 112 is formed in each of pixel regions 114. Adisplay region 110 of an image is constituted by the plurality of pixelregions 114. Incidentally, although detailed illustration is omitted, agate electrode of the TFT 112 of each of the pixel regions 114 isconnected to a gate bus line, and a drain electrode is connected to adrain bus line (data line). A source electrode of the TFT 112 isconnected to a pixel electrode formed in the pixel region 114. Theplurality of drain bus lines and gate bus lines are connected to aterminal portion 102 formed at the outer periphery of the arraysubstrate 116 and are connected to a driving circuit (not shown)provided at the outside.

A color filter (CF) substrate 104 formed to be smaller than the arraysubstrate 116 by a rough size of a region of the terminal portion 102seals liquid crystal to have a predetermined cell thickness (cell gap)and is provided opposite to the array substrate 116. Together with acommon electrode (common electrode; not shown) color filters (indicatedby characters of R (Red), G (Green) and B (Blue) in the drawing), BM(black Matrix; light shielding film) 108 and 118 using Cr (chromiumfilm) films etc., and the like are formed on the CF substrate 104. TheBM 118 is used for attaining a contrast by defining the plurality ofpixel regions 114 in the display region 110 and for preventing thegeneration of photoelectric leak current by shading the TFTs 112.Besides, the BM frame portion 108 is provided to shade the unnecessarylight from the outside of the display region 110. The array substrate116 and the CF substrate 104 are bonded to each other through a mainseal (sealing agent) 106 made of photo-curing resin.

Incidentally, a manufacturing process of a liquid crystal displayroughly includes an array process for forming a wiring pattern,switching elements (in the case of an active matrix type), and the likeon a glass substrate, a cell process for an alignment processing, anarrangement of a spacer, and sealing of liquid crystal between oppositeglass substrates, and a module process for attachment of a driver IC,mounting of a backlight, and the like. Among them, in the liquid crystalinjection process performed in the cell process, for example, a dipinjection method is used in which after the array substrate 116including the TFTs 112, and the color filter substrate 104 opposite tothat are bonded to each other through the main seal 106, liquid crystaland the substrates are put in a vacuum vessel, and an injection port(not shown) formed in the main seal 106 is immersed in the liquidcrystal, and then, the inside pressure of the vessel is returned to theatmospheric pressure to thereby seal the liquid crystal between thesubstrates.

On the other hand, in recent years, attention has been paid to adropping injection method in which for example, a prescribed amount ofliquid crystal is dropped onto a substrate surface in a frame of themain seal 106 formed into a frame shape around the array substrate 116,and the array substrate 116 and the CF substrate 104 are bonded to eachother in vacuum to seal the liquid crystal. According to the droppinginjection method, since the display panel 100 of the liquid crystaldisplay can be manufactured easily and at low cost, various technicalinvestigations and improvements have been carried out.

In the liquid crystal display using such a liquid crystal alignmentfixation technique, there is a problem concerning unevenness of displayin the vicinity of the injection port formed in the main seal 106 in thecase of using the dip injection method. Also in the case where a similarliquid crystal display is manufactured using the dropping injectionmethod, unevenness of display occurs in the vicinity of the main seal106.

FIG. 77 is a view for explaining a problem in the case where a sealingagent made of photo-curing resin is used for a liquid crystal injectionportion, which is used in the conventional dip injection method. Asshown in FIG. 77, when a light 122 having a wavelength range from anultraviolet range to a visible light range is irradiated to a sealingagent 126 of an injection port 120, a light 123 transmitted through thesealing agent 126 enters a liquid crystal layer 24. Photo-polymerizablecomponents dispersed in the liquid crystal layer 24 arephoto-polymerized by the light 123 transmitted through the sealing agent126 and an uneven display region 128 is produced near the injection port120.

FIG. 78 is a view for explaining a problem in the case where a main sealmade of photo-curing resin used in the conventional dropping injectionmethod is used. Even if a light 124 having a wavelength range from anultraviolet ray range to visible light range is incident from thedirection of a normal of a substrate surface, a partial light 125 isreflected by an array substrate 116 and enters a display region 110 tophoto-polymerize photo-polymerizable components in the vicinity of themain seal 106, and an uneven display region 128 is produced.

As shown in FIGS. 77 and 78, the light irradiated to the sealing agent126 for sealing the injection port 120 or to the main seal 106 entersthe display region 110, so that the photo-polymerizable components arephoto-polymerized before voltage application.

That is, although the photo-polymerizable components dispersed in theliquid crystal layer 24 form a cross-linking structure corresponding tothe liquid crystal alignment by photopolymerization, since thephoto-polymerizable components in the vicinity of the injection port 120or in the vicinity of the main seal 106 form a cross-linking structurein the vertical direction, even if a voltage is applied, the liquidcrystal molecules become hard to incline. There is no problem if thesealing agent 126 or the main seal 106 can be photo-cured in the statewhere the voltage is applied to the liquid crystal layer 24, however,since a manufacturing apparatus and a manufacturing process becomecomplicated, it is not realistic.

In order to solve this, in this embodiment, the above problem is solvedby means described below.

(1) A resin which can be photo-cured by a light in a range other thanthe photopolymerization wavelength range of the photo-polymerizablecomponent is used for the sealing agent 126 or the main seal 106. If thesealing agent 126 or the main seal 106 can be cured by the light in therange other than the wavelength range in which the photo-polymerizablecomponent is photo-polymerized, the above disadvantage does not occur.

Japanese Patent Unexamined Publication No. Hei. 11-2825 discloses such amanufacturing method that a sealing agent is irradiated with light inwhich a specified wavelength exerting a bad influence on liquid crystalis removed. However, this embodiment has an object not tophoto-polymerize the photo-polymerizable components dispersed in theliquid crystal at the process for curing the sealing agent 126 or themain seal 106, and is different from the well-known technique in that ifthe specified wavelength exerting a bad influence on the liquid crystalis such a wavelength that the photo-polymerizable components dispersedin the liquid crystal are not photo-polymerized, and the sealing agent126 or the main seal 106 is photo-cured, the light of the specifiedwavelength is also irradiated.

(2) A resin which can be photo-cured by a light having an intensity peakin a range other than the photopolymerization wavelength range of thephoto-polymerizable component is used for the sealing agent 126 or themain seal 106. Even in the resin partially requiring the light in thephotopolymerization wavelength range of the photo-polymerizablecomponent for photopolymerization, if the photo-curing wavelength rangeother than that is sufficiently wide, only the sealing agent 126 or themain seal 106 can be cured using the light having the intensity peak inthe range other than the photopolymerization wavelength range of thephoto-polymerizable component. That is, even if the photopolymerizationwavelength range of the photo-polymerizable component is partiallyincluded in the irradiation light, if the accumulation amount of lightin terms of the photopolymerization wavelength range of thephoto-polymerizable component is lowered than the accumulation amount oflight necessary for photopolymerization, the photo-polymerizablecomponent is not photo-polymerized. Thus, it becomes possible to cureonly the sealing agent 126 or the main seal 106 by the light having theintensity peak in the range other than the wavelength range in which thephoto-polymerizable component is photo-polymerized.

(3) The photo-curing resin used for the sealing agent 126 or the mainseal 106 is made to have a wavelength range of photo-curing longer thanat least the photo-polymerizable component. The photo-curing wavelengthrange depends on the light absorption characteristics of aphotoinitiator. Thus, if the absorption wavelength of the photoinitiatorcontained in the photo-curing resin is on the side of a longerwavelength than at least that of the photoinitiator contained in thephoto-polymerizable component, the light on the side of the longerwavelength than the wavelength range in which the photo-polymerizablecomponent is photo-polymerized is irradiated through a filter forblocking (cutting) a short wavelength side, and only the sealing agentor the main seal can be cured.

The reason why the long wavelength side, not the short wavelength side,is selected is that since many photoinitiators have light absorptionranges on the short wavelength side, if the short wavelength side isselected, it becomes difficult to distinguish between the photo-curingresin and the photo-polymerizable component, and if the light of theshort wavelength side is irradiated, a bad influence on the liquidcrystal becomes high.

(4) A light shielding structural member which hardly allows light topass through is arranged in a region near the injection port and outsidethe display region. By this, even if light is irradiated to theinjection port from the direction parallel to the substrate surface, thelight entering the display region is blocked by the light shieldingstructural member, so that only the sealing agent can be curedirrespective of the wavelength range of irradiation or the used resin.

(5) A light attenuation structural member for attenuating light to alevel not higher than a light amount at which the photo-polymerizablecomponent is photo-polymerized is arranged in a region near theinjection port and outside the display region. Even if the shieldingstructural member hardly transmitting light is not used, if the lightattenuation structural member is used which attenuates light to thevalue not higher than the light amount in which the photo-polymerizablecomponent is photo-polymerized, even if the light is irradiated to theinjection port from the direction parallel to the substrate surface, thelight entering the display region is attenuated by the light attenuationstructural member to the value not higher than the light amount in whichthe photo-polymerizable component is polymerized. Thus, only the sealingagent can be cured irrespective of the wavelength range of irradiationor the used resin.

(6) The above light shielding structural member or the light attenuationstructural member is made an aggregation made of plural structuralmembers each having a plane shape of a line or an almost circular form,and the structural members are alternately formed so that the liquidcrystal composite of the display region is not exposed when viewed inthe direction parallel to the substrate surface. If the structuralmember is separately formed, it obstructs the injection of liquidcrystal, however, by adopting the foregoing construction, the effectequivalent to the case where the structural member is separately formedcan be expected while the flow path of the liquid crystal is ensured.

By using the foregoing construction, in the liquid crystal display inwhich the liquid crystal alignment is fixed by photo-polymerizing thephoto-polymerizable components dispersed in the liquid crystal while thevoltage is applied, the occurrence of the unevenness of display in thevicinity of the injection port or in the vicinity of the main seal isprevented, and the high display quality can be obtained.

Hereinafter, the liquid crystal display according to this embodiment andthe method of manufacturing the same will be specifically describedusing examples and comparative examples.

Example 9-1

An acrylic photo-polymerizable component (made by Merck JapanCorporation) of 0.3 wt % exhibiting a nematic liquid crystal propertywas mixed into a negative liquid crystal (made by Merck JapanCorporation), so that a liquid crystal composite containing thephoto-polymerizable component was obtained. When a light absorptionspectrum of this liquid crystal composite was measured, it was foundthat as shown in FIG. 79, there was a wavelength range of approximately200 to 380 nm (range indicated by a bilateral arrow α1 of FIG. 79) inwhich photopolymerization occurred. Incidentally, although the lightabsorption spectrum of the liquid crystal single body was also measured,absorption by the liquid crystal was roughly 300 nm or less, and it wasunderstood that absorption at 300 nm or higher was caused by thephoto-polymerizable component.

Then, an acrylic resin (made by Toua Gosei Corporation) containing aphotoinitiator activated by light of a wide wavelength range including avisible light range was selected as a resin having a photo-curingwavelength range at the side of a longer wavelength than at least 380nm, and was used for the sealing agent 126. When the absorption spectrumof this resin was measured, as shown in FIG. 80, a wavelength range(range indicated by a bilateral arrows a2 of FIG. 80) existed in a rangeof approximately 200 to 600 nm, and since the wavelength range of 380 nmor longer was sufficiently wide, it was found that photo-curing can bemade by the light of 380 nm or longer.

The liquid crystal composite was injected into an empty panel of the MVAmode, and pressure extrusion was performed to make the cell thicknessuniform. Subsequently, the sealing agent 126 was coated on the injectionport, and after the pressurization was removed, light of a wavelengthrange of 380 to 600 nm was irradiated from the direction parallel to thesubstrate and the sealing agent 126 was cured. Incidentally, theselection of the wavelength range was performed with a metal halideoptical source and a filter (made by Asahi Bunko Corporation) forcutting a wavelength of 380 nm or less.

After the panel was formed, while a voltage not lower than thesaturation voltage at which the tilt orientation of the liquid crystalwas fixed was applied, ultraviolet rays were irradiated to thephoto-polymerizable component from the direction of a normal of asubstrate, and a cross-linking structure corresponding to the liquidcrystal alignment was formed. The obtained liquid crystal display wasset in a prober tester and a display test was performed.

Example 9-2

A liquid crystal composite containing a photo-polymerizable componentwas obtained by a similar method to the example 9-1. As a resinincluding a photo-curing wavelength range at the side of a longerwavelength than at least 380 nm, one similar to the example 9-1 was usedfor a main seal.

A frame pattern (main seal 106) closed by a sealing agent was formed ona substrate on which an alignment regulating structural member for theMVA was formed, a necessary amount of liquid crystal was dropped by adropping injection method, and bonding of substrates was performed undera reduced pressure. Subsequently, the substrates were exposed to theatmospheric pressure and the liquid crystal composite was diffused inthe main seal 106, so that a predetermined cell gap was obtained. Then,the light of the wavelength range of 380 to 600 nm was irradiatedthrough a color filter substrate in the direction of a normal of asubstrate surface to cure the main seal 106. Incidentally, the selectionof the wavelength range was performed with a metal halide light sourceand a filter (made by Asahi Bunko Corporation) for cutting thewavelength of 380 nm or less.

After the panel was formed, while a voltage not lower than thesaturation voltage at which the tilt orientation of the liquid crystalwas fixed was applied, ultraviolet rays were irradiated to thephoto-polymerizable component in the direction of a normal of asubstrate surface, and a cross-linking structure corresponding to theliquid crystal alignment was formed. The obtained liquid crystal displaywas set in a prober tester and a display test was carried out.

Example 9-3

A liquid crystal composite containing a photo-polymerizable componentwas obtained by a similar method to the example 9-1. An acrylic resin(made by Three Bond Corporation) containing a photoinitiator activatedby light of a wavelength range including a part of a visible light rangewas selected as a resin having a wavelength range of photopolymerizationon the side of a longer wavelength than at least 380 nm, and was usedfor a sealing agent. When the absorption spectrum of this resin wasmeasured, as shown by a curved line β1 of FIG. 81, a wavelength range(range indicated by a bilateral arrow α3 of FIG. 81) ofphotopolymerization existed at approximately 200 to 450 nm, and sincethe wavelength range of 380 nm or longer was not very wide (rangeindicated by a bilateral arrow α4 of FIG. 81), it was found that a partof light of a wavelength range not longer than 380 nm was alsonecessary. Incidentally, as indicated by a curved line β2, a generalphoto-curing resin has a wavelength range of photopolymerization fromapproximately 200 to 380 nm, and contains a photoinitiator activated byonly light of an ultraviolet ray region.

The liquid crystal composite was injected into an empty panel of the MVAmode, and pressure extrusion was carried out to make the cell thicknessuniform. Subsequently, a sealing agent was coated on an injection port,and after the pressurization was removed, light of a wavelength range(range indicated by a bilateral arrow α5 of FIG. 81) of 350 to 600 nmwas irradiated from the direction parallel to the substrate and thesealing agent was cured. Since the photo-polymerizable componentsdispersed in the liquid crystal are photo-polymerized when anaccumulation amount of light in the vicinity of the i line (330 to 380nm) becomes 1000 mJ/cm² or higher, the amount of irradiation light wasset such that the accumulation amount of light in the wavelength rangeof 350 to 380 nm became this value or less. The selection of thewavelength range was carried out with a high pressure mercury lightsource and a filter (made by Asahi Bunko Corporation) for cutting awavelength of 350 nm or less. A wavelength at which the intensity has apeak becomes 436 nm from 365 nm by this filter, and the accumulationamount of light in the vicinity of the i line is attenuated toapproximately ⅓. Although the amount of light by which the photo-curingresin is photo-cured is 2000 mJ/cm² in the accumulation amount of lightof the wavelength range of 350 to 600 nm, since the accumulation amountof light in the vicinity of the i line becomes 1000 mJ/cm² or less bythe filter, it has been found that only the sealing agent can be cured.

After the panel was formed, while a voltage not lower than thesaturation voltage at which the tilt orientation of the liquid crystalwas fixed was applied, ultraviolet rays were irradiated to thephoto-polymerizable component from the direction of a normal of asubstrate surface, and a cross-linking structure was formed. Theobtained liquid crystal display was set in a prober tester and a displaytest was carried out.

Example 9-4

A liquid crystal composite containing a photo-polymerizable componentwas obtained by a similar method to the example 9-1. As a sealing agent,the foregoing general photo-curing resin (made by Three BondCorporation) was used in which an accumulation amount of light necessaryfor curing was 2000 mJ in terms of the i line. In an empty panel of anMVA-LCD prior to sealing of liquid crystal, as shown in FIGS. 82A and82B (FIG. 82A shows a state viewed in the direction of a normal of asubstrate surface, and FIG. 82B shows a state viewed in the direction ofthe substrate surface), a light shielding structural member 130 whichwas almost opaque to light was formed in the vicinity of an injectionport and a region outside a display region. The light shieldingstructural member 130 was made an aggregate constituted by pluralstructural members each having a plane shape of a substantially circularform, and they were alternately arranged so that the liquid crystalcomposite of a display region 110 was not exposed when viewed in thedirection parallel to the substrate surface. The structural members wereformed by dotting a seal agent (made by Kyoritsu Chemical Corporation)mixed with a black spacer (Sekisui Fine Chemical Corporation) by a sealdispenser.

The liquid crystal composite was injected into this empty panel, andpressure extrusion was carried out to make the cell gap uniform.Subsequently, the sealing agent was coated on the injection port, andafter the pressurization was removed, light of a wavelength range of 200to 600 nm was irradiated from the direction parallel to the substrate tocure the sealing agent. In this example 9-4, the light from a highpressure mercury light source was irradiated as it was.

After the panel was formed, while the voltage not lower than thesaturation voltage at which the tilt orientation of liquid crystal wasfixed was applied, ultraviolet rays were irradiated to thephoto-polymerizable component in the direction of a normal of asubstrate, and a cross-linking structure corresponding to the liquidcrystal alignment was formed. The obtained liquid crystal display wasset in a prober tester, and a display test was carried out.

Example 9-5

A liquid crystal composite containing a photo-polymerizable componentwas obtained by a method similar to the example 9-1. The foregoinggeneral photo-curing resin was used as a sealing agent. In an emptypanel of the MVA mode, as shown in FIG. 83, a light attenuationstructural member 132 for attenuating light to a level not higher thanan amount of light at which the photo-polymerizable component wasphoto-polymerized was formed in the vicinity of an injection port 120and in a region outside a display region. The light attenuationstructural member 132 was made an aggregate constituted by pluralstructural members each having a plane shape of a line, and they werealternately arranged so that the liquid crystal composite of a displayregion 110 was not exposed when viewed in the direction parallel to thesubstrate surface. The light attenuation structural member 132 wasformed by bundling a main seal and a sealing agent mixed with a fiberspacer (made by Nippon Electric Glass Corporation/spacer mixed as a gapagent of a main seal) by a seal dispenser. Since the width of thestructural member is about 1 mm, the above seal agent of a thickness of1 mm was coated on the glass, light of a wavelength range of 200 to 600nm was irradiated, and the level of attenuation of the accumulationamount of light in the vicinity of the i line was measured. As a result,since the accumulation amount of light in the vicinity of the i line isattenuated to ⅓ by the above seal agent, it has been found that even ifthe light of the wavelength range of 200 to 600 nm is irradiated, onlythe sealing agent can be cured if irradiation is performed through theseal agent.

The liquid crystal composite was injected into this empty panel andpressure extrusion was carried out to make the cell thickness uniform.Subsequently, the sealing agent (not shown) was coated on an injectionport 120, and after pressurization was removed, light of a wavelengthrange of 200 to 600 nm was irradiated from the direction parallel to thesubstrate to cure the sealing agent. In the example 4, the light from ahigh pressure mercury light source was irradiated as it was.

After the panel was formed, while a voltage not lower than thesaturation voltage at which the tilt orientation of liquid crystal wasfixed was applied, ultraviolet rays were irradiated to the componentfrom the direction of a normal of a substrate, and a cross-linkingstructure corresponding to the liquid crystal alignment was formed. Theobtained liquid crystal display was set in a prober tester and a displaytest was carried out.

Conventional Example 9-1

A liquid crystal composite containing a photo-polymerizable componentwas obtained by a method similar to the example 9-1. The foregoinggeneral photo-curing resin was used as a sealing agent. In an emptypanel of an MVA mode, anything was not formed in the vicinity of aninjection port. The liquid crystal composite was injected into thisempty panel, and pressure extrusion was carried out to make the cellthickness uniform. Subsequently, the sealing agent was coated on theinjection port, and after pressurization was removed, light of awavelength range of 200 to 600 nm was irradiated from the directionparallel to the substrate to cure the sealing agent. In thisconventional example 9-1, the light from a high pressure mercury lightsource was irradiated as it was.

After the panel was formed, while a voltage not lower than thesaturation voltage at which the tilt orientation of the liquid crystalwas fixed was applied, ultraviolet rays were irradiated to the componentfrom the direction of a normal of the substrate, and a cross-linkingstructure corresponding to the liquid crystal alignment was formed. Theobtained liquid crystal display was set in a prober tester and a displaytest was carried out.

Conventional Example 9-2

A liquid crystal composite containing a photo-polymerizable componentwas obtained by a method similar to the example 9-1. An epoxy resin(made by Kyoritsu Chemical Corporation) containing a photoinitiatoractivated by only light of an ultraviolet ray region was used for a mainseal.

A frame pattern closed by the main seal was formed on a substrate inwhich an alignment control member for the MVA was formed, a necessaryamount of liquid crystal was dropped, and bonding of substrates wascarried out under a reduced pressure. Subsequently, a gap was ensured bythe opening to the atmosphere, and the liquid crystal composite wasdiffused in the frame pattern. Then, light of a wavelength range of 200to 600 nm was irradiated through a CF substrate from the directionvertical to the substrate and the main seal was cured. In thisconventional example 9-2, the light from a high pressure mercury lightsource was irradiated as it was.

After the panel was formed, while a voltage not lower than thesaturation voltage at which the tilt orientation of the liquid crystalwas fixed was applied, ultraviolet rays were irradiated to thephoto-polymerizable component from the direction of a normal of thesubstrate, and a cross-linking structure corresponding to a liquidcrystal alignment was formed. The obtained liquid crystal display wasset in a prober tester and a display test was carried out.

[Results of Display Test]

In the liquid crystal displays of the examples 9-1 to 9-5, unevenness ofdisplay did not occur at a halftone display, whereas in the conventionalexamples 9-1 and 9-2, unevenness of display occurred in the vicinity ofthe injection port or the main seal.

As described above, according to this embodiment, in the liquid crystaldisplay adopting the alignment fixation system in which the liquidcrystal composite containing the photo-polymerizable component issandwiched between the substrates, and the photo-polymerizable componentis photo-polymerized while a voltage is applied to the liquid crystalcomposite, it can be manufactured at a high yield while display qualityis improved.

As described above, according to the present invention, the alignmentorientation of the liquid crystal is regulated by using the polymerfixing method, and a wide angle of view is obtained, and further, aresponse time at a halftone can be shortened, so that excellent displayquality can be obtained.

1. A method of manufacturing a liquid crystal display, comprising thesteps of: sealing a liquid crystal layer containing a polymerizablecomponent, which is polymerized by light or heat, between substrates;and polymerizing the polymerizable component without applying a voltageto the liquid crystal layer to regulate a pretilt angle of a liquidcrystal molecule and/or a tilt direction at a time of driving.
 2. Amethod of manufacturing a liquid crystal display according to claim 1,wherein an alignment film is formed on the substrate using an opticalalignment processing.
 3. A method of manufacturing a liquid crystaldisplay according to claim 1, wherein an alignment regulating structuralmember is formed on the substrate.
 4. A method of manufacturing a liquidcrystal display according to claim 1, wherein the polymerizablecomponent is a mesomorphism or non-mesogenic monomer.
 5. A method ofmanufacturing a liquid crystal display according to claim 4, wherein themesomorphism or non-mesogenic monomer is bifunctional acrylate or amixture of bifunctional acrylate and monofunctional acrylate.